diff --git a/src/JsonSchema/Constraints/ObjectConstraint.php b/src/JsonSchema/Constraints/ObjectConstraint.php
index 9dc0b188..acaaf7c3 100644
--- a/src/JsonSchema/Constraints/ObjectConstraint.php
+++ b/src/JsonSchema/Constraints/ObjectConstraint.php
@@ -77,7 +77,7 @@ public function validateElement($element, $matches, $objectDefinition = null, $p
 
             // no additional properties allowed
             if (!in_array($i, $matches) && $additionalProp === false && $this->inlineSchemaProperty !== $i && !$definition) {
-                $this->addError($path, "The property " . $i . " is not defined and the definition does not allow additional properties");
+                $this->addError($path, "The property - " . $i . " - is not defined and the definition does not allow additional properties");
             }
 
             // additional properties defined
diff --git a/tests/JsonSchema/Tests/Constraints/AdditionalPropertiesTest.php b/tests/JsonSchema/Tests/Constraints/AdditionalPropertiesTest.php
index 9df7ae39..07e7f098 100644
--- a/tests/JsonSchema/Tests/Constraints/AdditionalPropertiesTest.php
+++ b/tests/JsonSchema/Tests/Constraints/AdditionalPropertiesTest.php
@@ -36,7 +36,7 @@ public function getInvalidTests()
                 array(
                     array(
                         'property' => '',
-                        'message'  => 'The property additionalProp is not defined and the definition does not allow additional properties'
+                        'message'  => 'The property - additionalProp - is not defined and the definition does not allow additional properties'
                     )
                 )
             ),