diff --git a/lib/ast-converter.js b/lib/ast-converter.js
index 36db57c..cb74058 100644
--- a/lib/ast-converter.js
+++ b/lib/ast-converter.js
@@ -752,6 +752,14 @@ module.exports = function(ast, extra) {
                     type: "Identifier",
                     name: ts.unescapeIdentifier(node.text)
                 });
+                if (node.parent.questionToken && (
+                    SyntaxKind.Parameter === node.parent.kind ||
+                    SyntaxKind.PropertyDeclaration === node.parent.kind ||
+                    SyntaxKind.PropertySignature === node.parent.kind ||
+                    SyntaxKind.MethodSignature === node.parent.kind
+                )) {
+                    result.optional = true;
+                }
                 break;
 
             case SyntaxKind.WithStatement:
diff --git a/tests/fixtures/typescript/basics/class-with-optional-properties.result.js b/tests/fixtures/typescript/basics/class-with-optional-properties.result.js
new file mode 100644
index 0000000..0a6d6f8
--- /dev/null
+++ b/tests/fixtures/typescript/basics/class-with-optional-properties.result.js
@@ -0,0 +1,526 @@
+module.exports = {
+    "body": [
+        {
+            "body": {
+                "body": [
+                    {
+                        "accessibility": null,
+                        "computed": false,
+                        "decorators": [],
+                        "key": {
+                            "loc": {
+                                "end": {
+                                    "column": 5,
+                                    "line": 2
+                                },
+                                "start": {
+                                    "column": 2,
+                                    "line": 2
+                                }
+                            },
+                            "name": "foo",
+                            "optional": true,
+                            "range": [
+                                14,
+                                17
+                            ],
+                            "type": "Identifier"
+                        },
+                        "loc": {
+                            "end": {
+                                "column": 7,
+                                "line": 2
+                            },
+                            "start": {
+                                "column": 2,
+                                "line": 2
+                            }
+                        },
+                        "range": [
+                            14,
+                            19
+                        ],
+                        "static": false,
+                        "type": "ClassProperty",
+                        "value": null
+                    },
+                    {
+                        "accessibility": null,
+                        "computed": false,
+                        "decorators": [],
+                        "key": {
+                            "loc": {
+                                "end": {
+                                    "column": 5,
+                                    "line": 3
+                                },
+                                "start": {
+                                    "column": 2,
+                                    "line": 3
+                                }
+                            },
+                            "name": "bar",
+                            "optional": true,
+                            "range": [
+                                22,
+                                25
+                            ],
+                            "type": "Identifier"
+                        },
+                        "loc": {
+                            "end": {
+                                "column": 16,
+                                "line": 3
+                            },
+                            "start": {
+                                "column": 2,
+                                "line": 3
+                            }
+                        },
+                        "range": [
+                            22,
+                            36
+                        ],
+                        "static": false,
+                        "type": "ClassProperty",
+                        "value": null
+                    },
+                    {
+                        "accessibility": "private",
+                        "computed": false,
+                        "decorators": [],
+                        "key": {
+                            "loc": {
+                                "end": {
+                                    "column": 13,
+                                    "line": 4
+                                },
+                                "start": {
+                                    "column": 10,
+                                    "line": 4
+                                }
+                            },
+                            "name": "baz",
+                            "optional": true,
+                            "range": [
+                                47,
+                                50
+                            ],
+                            "type": "Identifier"
+                        },
+                        "loc": {
+                            "end": {
+                                "column": 24,
+                                "line": 4
+                            },
+                            "start": {
+                                "column": 2,
+                                "line": 4
+                            }
+                        },
+                        "range": [
+                            39,
+                            61
+                        ],
+                        "static": false,
+                        "type": "ClassProperty",
+                        "value": null
+                    }
+                ],
+                "loc": {
+                    "end": {
+                        "column": 1,
+                        "line": 5
+                    },
+                    "start": {
+                        "column": 10,
+                        "line": 1
+                    }
+                },
+                "range": [
+                    10,
+                    63
+                ],
+                "type": "ClassBody"
+            },
+            "decorators": [],
+            "id": {
+                "loc": {
+                    "end": {
+                        "column": 9,
+                        "line": 1
+                    },
+                    "start": {
+                        "column": 6,
+                        "line": 1
+                    }
+                },
+                "name": "Foo",
+                "range": [
+                    6,
+                    9
+                ],
+                "type": "Identifier"
+            },
+            "implements": [],
+            "loc": {
+                "end": {
+                    "column": 1,
+                    "line": 5
+                },
+                "start": {
+                    "column": 0,
+                    "line": 1
+                }
+            },
+            "range": [
+                0,
+                63
+            ],
+            "superClass": null,
+            "type": "ClassDeclaration"
+        }
+    ],
+    "loc": {
+        "end": {
+            "column": 1,
+            "line": 5
+        },
+        "start": {
+            "column": 0,
+            "line": 1
+        }
+    },
+    "range": [
+        0,
+        63
+    ],
+    "sourceType": "script",
+    "tokens": [
+        {
+            "loc": {
+                "end": {
+                    "column": 5,
+                    "line": 1
+                },
+                "start": {
+                    "column": 0,
+                    "line": 1
+                }
+            },
+            "range": [
+                0,
+                5
+            ],
+            "type": "Keyword",
+            "value": "class"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 9,
+                    "line": 1
+                },
+                "start": {
+                    "column": 6,
+                    "line": 1
+                }
+            },
+            "range": [
+                6,
+                9
+            ],
+            "type": "Identifier",
+            "value": "Foo"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 11,
+                    "line": 1
+                },
+                "start": {
+                    "column": 10,
+                    "line": 1
+                }
+            },
+            "range": [
+                10,
+                11
+            ],
+            "type": "Punctuator",
+            "value": "{"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 5,
+                    "line": 2
+                },
+                "start": {
+                    "column": 2,
+                    "line": 2
+                }
+            },
+            "range": [
+                14,
+                17
+            ],
+            "type": "Identifier",
+            "value": "foo"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 6,
+                    "line": 2
+                },
+                "start": {
+                    "column": 5,
+                    "line": 2
+                }
+            },
+            "range": [
+                17,
+                18
+            ],
+            "type": "Punctuator",
+            "value": "?"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 7,
+                    "line": 2
+                },
+                "start": {
+                    "column": 6,
+                    "line": 2
+                }
+            },
+            "range": [
+                18,
+                19
+            ],
+            "type": "Punctuator",
+            "value": ";"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 5,
+                    "line": 3
+                },
+                "start": {
+                    "column": 2,
+                    "line": 3
+                }
+            },
+            "range": [
+                22,
+                25
+            ],
+            "type": "Identifier",
+            "value": "bar"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 6,
+                    "line": 3
+                },
+                "start": {
+                    "column": 5,
+                    "line": 3
+                }
+            },
+            "range": [
+                25,
+                26
+            ],
+            "type": "Punctuator",
+            "value": "?"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 8,
+                    "line": 3
+                },
+                "start": {
+                    "column": 7,
+                    "line": 3
+                }
+            },
+            "range": [
+                27,
+                28
+            ],
+            "type": "Punctuator",
+            "value": ":"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 15,
+                    "line": 3
+                },
+                "start": {
+                    "column": 9,
+                    "line": 3
+                }
+            },
+            "range": [
+                29,
+                35
+            ],
+            "type": "Identifier",
+            "value": "string"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 16,
+                    "line": 3
+                },
+                "start": {
+                    "column": 15,
+                    "line": 3
+                }
+            },
+            "range": [
+                35,
+                36
+            ],
+            "type": "Punctuator",
+            "value": ";"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 9,
+                    "line": 4
+                },
+                "start": {
+                    "column": 2,
+                    "line": 4
+                }
+            },
+            "range": [
+                39,
+                46
+            ],
+            "type": "Keyword",
+            "value": "private"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 13,
+                    "line": 4
+                },
+                "start": {
+                    "column": 10,
+                    "line": 4
+                }
+            },
+            "range": [
+                47,
+                50
+            ],
+            "type": "Identifier",
+            "value": "baz"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 14,
+                    "line": 4
+                },
+                "start": {
+                    "column": 13,
+                    "line": 4
+                }
+            },
+            "range": [
+                50,
+                51
+            ],
+            "type": "Punctuator",
+            "value": "?"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 16,
+                    "line": 4
+                },
+                "start": {
+                    "column": 15,
+                    "line": 4
+                }
+            },
+            "range": [
+                52,
+                53
+            ],
+            "type": "Punctuator",
+            "value": ":"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 23,
+                    "line": 4
+                },
+                "start": {
+                    "column": 17,
+                    "line": 4
+                }
+            },
+            "range": [
+                54,
+                60
+            ],
+            "type": "Identifier",
+            "value": "string"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 24,
+                    "line": 4
+                },
+                "start": {
+                    "column": 23,
+                    "line": 4
+                }
+            },
+            "range": [
+                60,
+                61
+            ],
+            "type": "Punctuator",
+            "value": ";"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 1,
+                    "line": 5
+                },
+                "start": {
+                    "column": 0,
+                    "line": 5
+                }
+            },
+            "range": [
+                62,
+                63
+            ],
+            "type": "Punctuator",
+            "value": "}"
+        }
+    ],
+    "type": "Program"
+};
diff --git a/tests/fixtures/typescript/basics/class-with-optional-properties.src.ts b/tests/fixtures/typescript/basics/class-with-optional-properties.src.ts
new file mode 100644
index 0000000..536aab8
--- /dev/null
+++ b/tests/fixtures/typescript/basics/class-with-optional-properties.src.ts
@@ -0,0 +1,5 @@
+class Foo {
+  foo?;
+  bar? : string;
+  private baz? : string;
+}
diff --git a/tests/fixtures/typescript/basics/function-with-object-type-with-optional-properties.result.js b/tests/fixtures/typescript/basics/function-with-object-type-with-optional-properties.result.js
new file mode 100644
index 0000000..ad9e503
--- /dev/null
+++ b/tests/fixtures/typescript/basics/function-with-object-type-with-optional-properties.result.js
@@ -0,0 +1,768 @@
+module.exports = {
+    "body": [
+        {
+            "async": false,
+            "body": {
+                "body": [],
+                "loc": {
+                    "end": {
+                        "column": 1,
+                        "line": 3
+                    },
+                    "start": {
+                        "column": 47,
+                        "line": 1
+                    }
+                },
+                "range": [
+                    47,
+                    51
+                ],
+                "type": "BlockStatement"
+            },
+            "expression": false,
+            "generator": false,
+            "id": {
+                "loc": {
+                    "end": {
+                        "column": 12,
+                        "line": 1
+                    },
+                    "start": {
+                        "column": 9,
+                        "line": 1
+                    }
+                },
+                "name": "foo",
+                "range": [
+                    9,
+                    12
+                ],
+                "type": "Identifier"
+            },
+            "loc": {
+                "end": {
+                    "column": 1,
+                    "line": 3
+                },
+                "start": {
+                    "column": 0,
+                    "line": 1
+                }
+            },
+            "params": [
+                {
+                    "loc": {
+                        "end": {
+                            "column": 23,
+                            "line": 1
+                        },
+                        "start": {
+                            "column": 13,
+                            "line": 1
+                        }
+                    },
+                    "properties": [
+                        {
+                            "computed": false,
+                            "key": {
+                                "loc": {
+                                    "end": {
+                                        "column": 17,
+                                        "line": 1
+                                    },
+                                    "start": {
+                                        "column": 14,
+                                        "line": 1
+                                    }
+                                },
+                                "name": "bar",
+                                "range": [
+                                    14,
+                                    17
+                                ],
+                                "type": "Identifier"
+                            },
+                            "kind": "init",
+                            "loc": {
+                                "end": {
+                                    "column": 17,
+                                    "line": 1
+                                },
+                                "start": {
+                                    "column": 14,
+                                    "line": 1
+                                }
+                            },
+                            "method": false,
+                            "range": [
+                                14,
+                                17
+                            ],
+                            "shorthand": true,
+                            "type": "Property",
+                            "value": {
+                                "loc": {
+                                    "end": {
+                                        "column": 17,
+                                        "line": 1
+                                    },
+                                    "start": {
+                                        "column": 14,
+                                        "line": 1
+                                    }
+                                },
+                                "name": "bar",
+                                "range": [
+                                    14,
+                                    17
+                                ],
+                                "type": "Identifier"
+                            }
+                        },
+                        {
+                            "computed": false,
+                            "key": {
+                                "loc": {
+                                    "end": {
+                                        "column": 22,
+                                        "line": 1
+                                    },
+                                    "start": {
+                                        "column": 19,
+                                        "line": 1
+                                    }
+                                },
+                                "name": "baz",
+                                "range": [
+                                    19,
+                                    22
+                                ],
+                                "type": "Identifier"
+                            },
+                            "kind": "init",
+                            "loc": {
+                                "end": {
+                                    "column": 22,
+                                    "line": 1
+                                },
+                                "start": {
+                                    "column": 19,
+                                    "line": 1
+                                }
+                            },
+                            "method": false,
+                            "range": [
+                                19,
+                                22
+                            ],
+                            "shorthand": true,
+                            "type": "Property",
+                            "value": {
+                                "loc": {
+                                    "end": {
+                                        "column": 22,
+                                        "line": 1
+                                    },
+                                    "start": {
+                                        "column": 19,
+                                        "line": 1
+                                    }
+                                },
+                                "name": "baz",
+                                "range": [
+                                    19,
+                                    22
+                                ],
+                                "type": "Identifier"
+                            }
+                        }
+                    ],
+                    "range": [
+                        13,
+                        23
+                    ],
+                    "type": "ObjectPattern",
+                    "typeAnnotation": {
+                        "loc": {
+                            "end": {
+                                "column": 45,
+                                "line": 1
+                            },
+                            "start": {
+                                "column": 25,
+                                "line": 1
+                            }
+                        },
+                        "range": [
+                            25,
+                            45
+                        ],
+                        "type": "TypeAnnotation",
+                        "typeAnnotation": {
+                            "loc": {
+                                "end": {
+                                    "column": 45,
+                                    "line": 1
+                                },
+                                "start": {
+                                    "column": 25,
+                                    "line": 1
+                                }
+                            },
+                            "members": [
+                                {
+                                    "loc": {
+                                        "end": {
+                                            "column": 39,
+                                            "line": 1
+                                        },
+                                        "start": {
+                                            "column": 26,
+                                            "line": 1
+                                        }
+                                    },
+                                    "name": {
+                                        "loc": {
+                                            "end": {
+                                                "column": 29,
+                                                "line": 1
+                                            },
+                                            "start": {
+                                                "column": 26,
+                                                "line": 1
+                                            }
+                                        },
+                                        "name": "bar",
+                                        "optional": true,
+                                        "range": [
+                                            26,
+                                            29
+                                        ],
+                                        "type": "Identifier"
+                                    },
+                                    "questionToken": {
+                                        "loc": {
+                                            "end": {
+                                                "column": 30,
+                                                "line": 1
+                                            },
+                                            "start": {
+                                                "column": 29,
+                                                "line": 1
+                                            }
+                                        },
+                                        "range": [
+                                            29,
+                                            30
+                                        ],
+                                        "type": "TSQuestionToken"
+                                    },
+                                    "range": [
+                                        26,
+                                        39
+                                    ],
+                                    "type": "TSPropertySignature",
+                                    "typeAnnotation": {
+                                        "loc": {
+                                            "end": {
+                                                "column": 38,
+                                                "line": 1
+                                            },
+                                            "start": {
+                                                "column": 32,
+                                                "line": 1
+                                            }
+                                        },
+                                        "range": [
+                                            32,
+                                            38
+                                        ],
+                                        "type": "TypeAnnotation",
+                                        "typeAnnotation": {
+                                            "loc": {
+                                                "end": {
+                                                    "column": 38,
+                                                    "line": 1
+                                                },
+                                                "start": {
+                                                    "column": 32,
+                                                    "line": 1
+                                                }
+                                            },
+                                            "range": [
+                                                32,
+                                                38
+                                            ],
+                                            "type": "TSStringKeyword"
+                                        }
+                                    }
+                                },
+                                {
+                                    "loc": {
+                                        "end": {
+                                            "column": 44,
+                                            "line": 1
+                                        },
+                                        "start": {
+                                            "column": 40,
+                                            "line": 1
+                                        }
+                                    },
+                                    "name": {
+                                        "loc": {
+                                            "end": {
+                                                "column": 43,
+                                                "line": 1
+                                            },
+                                            "start": {
+                                                "column": 40,
+                                                "line": 1
+                                            }
+                                        },
+                                        "name": "baz",
+                                        "optional": true,
+                                        "range": [
+                                            40,
+                                            43
+                                        ],
+                                        "type": "Identifier"
+                                    },
+                                    "questionToken": {
+                                        "loc": {
+                                            "end": {
+                                                "column": 44,
+                                                "line": 1
+                                            },
+                                            "start": {
+                                                "column": 43,
+                                                "line": 1
+                                            }
+                                        },
+                                        "range": [
+                                            43,
+                                            44
+                                        ],
+                                        "type": "TSQuestionToken"
+                                    },
+                                    "range": [
+                                        40,
+                                        44
+                                    ],
+                                    "type": "TSPropertySignature",
+                                    "typeAnnotation": null
+                                }
+                            ],
+                            "range": [
+                                25,
+                                45
+                            ],
+                            "type": "TSTypeLiteral"
+                        }
+                    }
+                }
+            ],
+            "range": [
+                0,
+                51
+            ],
+            "type": "FunctionDeclaration"
+        }
+    ],
+    "loc": {
+        "end": {
+            "column": 1,
+            "line": 3
+        },
+        "start": {
+            "column": 0,
+            "line": 1
+        }
+    },
+    "range": [
+        0,
+        51
+    ],
+    "sourceType": "script",
+    "tokens": [
+        {
+            "loc": {
+                "end": {
+                    "column": 8,
+                    "line": 1
+                },
+                "start": {
+                    "column": 0,
+                    "line": 1
+                }
+            },
+            "range": [
+                0,
+                8
+            ],
+            "type": "Keyword",
+            "value": "function"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 12,
+                    "line": 1
+                },
+                "start": {
+                    "column": 9,
+                    "line": 1
+                }
+            },
+            "range": [
+                9,
+                12
+            ],
+            "type": "Identifier",
+            "value": "foo"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 13,
+                    "line": 1
+                },
+                "start": {
+                    "column": 12,
+                    "line": 1
+                }
+            },
+            "range": [
+                12,
+                13
+            ],
+            "type": "Punctuator",
+            "value": "("
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 14,
+                    "line": 1
+                },
+                "start": {
+                    "column": 13,
+                    "line": 1
+                }
+            },
+            "range": [
+                13,
+                14
+            ],
+            "type": "Punctuator",
+            "value": "{"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 17,
+                    "line": 1
+                },
+                "start": {
+                    "column": 14,
+                    "line": 1
+                }
+            },
+            "range": [
+                14,
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diff --git a/tests/fixtures/typescript/basics/function-with-object-type-with-optional-properties.src.ts b/tests/fixtures/typescript/basics/function-with-object-type-with-optional-properties.src.ts
new file mode 100644
index 0000000..49837b4
--- /dev/null
+++ b/tests/fixtures/typescript/basics/function-with-object-type-with-optional-properties.src.ts
@@ -0,0 +1,3 @@
+function foo({bar, baz}: {bar?: string, baz?}) {
+
+}
diff --git a/tests/fixtures/typescript/basics/interface-with-optional-properties.result.js b/tests/fixtures/typescript/basics/interface-with-optional-properties.result.js
new file mode 100644
index 0000000..346edb1
--- /dev/null
+++ b/tests/fixtures/typescript/basics/interface-with-optional-properties.result.js
@@ -0,0 +1,813 @@
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+                }
+            },
+            "range": [
+                78,
+                79
+            ],
+            "type": "Punctuator",
+            "value": ";"
+        },
+        {
+            "loc": {
+                "end": {
+                    "column": 1,
+                    "line": 5
+                },
+                "start": {
+                    "column": 0,
+                    "line": 5
+                }
+            },
+            "range": [
+                80,
+                81
+            ],
+            "type": "Punctuator",
+            "value": "}"
+        }
+    ],
+    "type": "Program"
+};
diff --git a/tests/fixtures/typescript/basics/interface-with-optional-properties.src.ts b/tests/fixtures/typescript/basics/interface-with-optional-properties.src.ts
new file mode 100644
index 0000000..448d419
--- /dev/null
+++ b/tests/fixtures/typescript/basics/interface-with-optional-properties.src.ts
@@ -0,0 +1,5 @@
+interface test {
+    foo?;
+    bar?: string;
+    baz?(foo, bar?: string, baz?);
+}
diff --git a/tests/fixtures/typescript/basics/non-null-assertion-operator.result.js b/tests/fixtures/typescript/basics/non-null-assertion-operator.result.js
index 9fa6cc7..3cab39a 100644
--- a/tests/fixtures/typescript/basics/non-null-assertion-operator.result.js
+++ b/tests/fixtures/typescript/basics/non-null-assertion-operator.result.js
@@ -70,6 +70,7 @@ module.exports = {
                         }
                     },
                     "name": "e",
+                    "optional": true,
                     "typeAnnotation": {
                         "type": "TypeAnnotation",
                         "loc": {
@@ -760,4 +761,4 @@ module.exports = {
             }
         }
     ]
-};
\ No newline at end of file
+};