diff --git a/plugin.go b/plugin.go
index 70b808f..499a235 100644
--- a/plugin.go
+++ b/plugin.go
@@ -21,6 +21,8 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
+var errSkip = fmt.Errorf("skip")
+
 // Plugin defines the S3 plugin parameters.
 type Plugin struct {
 	Endpoint              string
@@ -167,9 +169,16 @@ func (p *Plugin) Exec() error {
 	anyMatched := false
 
 	for _, match := range matches {
-		// skip directories
-		if isDir(match, matches) {
-			continue
+		// check directories and fail if directory without glob pattern
+		if err := isDir(match, matches); err != nil {
+			if err == errSkip {
+				continue
+			}
+			log.WithFields(log.Fields{
+				"error": err,
+				"match": match,
+			}).Error("Directory specified without glob pattern")
+			return err
 		}
 
 		// Preview stripping (wildcard for absolute patterns, literal for relative patterns)
@@ -411,11 +420,11 @@ func resolveSource(sourceDir, source, stripPrefix string) string {
 	return stripPrefix + path
 }
 
-// checks if the source path is a dir
-func isDir(source string, matches []string) bool {
+// checks if the source path is a dir and returns error if directory found without glob patterns
+func isDir(source string, matches []string) error {
 	stat, err := os.Stat(source)
 	if err != nil {
-		return true // should never happen
+		return errSkip // skip non-existent files
 	}
 	if stat.IsDir() {
 		count := 0
@@ -425,11 +434,11 @@ func isDir(source string, matches []string) bool {
 			}
 		}
 		if count <= 1 {
-			log.Warnf("Skipping '%s' since it is a directory. Please use correct glob expression if this is unexpected.", source)
+			return fmt.Errorf("directory '%s' specified without glob pattern. Use a pattern like '%s/*' or '%s/**' to upload directory contents", source, source, source)
 		}
-		return true
+		return errSkip // skip directory but allow its children to be processed
 	}
-	return false
+	return nil
 }
 
 // normalizePath converts the path to a forward slash format and trims the prefix.
diff --git a/plugin_test.go b/plugin_test.go
new file mode 100644
index 0000000..7f900a9
--- /dev/null
+++ b/plugin_test.go
@@ -0,0 +1,91 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestIsDir(t *testing.T) {
+	// Create temporary directory for testing
+	tmpDir := t.TempDir()
+	testDir := filepath.Join(tmpDir, "testdir")
+	testFile := filepath.Join(tmpDir, "testfile.txt")
+
+	// Create a test directory
+	err := os.Mkdir(testDir, 0755)
+	if err != nil {
+		t.Fatalf("Failed to create test directory: %v", err)
+	}
+
+	// Create a test file
+	file, err := os.Create(testFile)
+	if err != nil {
+		t.Fatalf("Failed to create test file: %v", err)
+	}
+	file.Close()
+
+	tests := []struct {
+		name        string
+		source      string
+		matches     []string
+		expectError bool
+		expectSkip  bool
+		errorContains string
+	}{
+		{
+			name:        "file should not error",
+			source:      testFile,
+			matches:     []string{testFile},
+			expectError: false,
+			expectSkip:  false,
+		},
+		{
+			name:        "directory without glob should error", 
+			source:      testDir,
+			matches:     []string{testDir},
+			expectError: true,
+			expectSkip:  false,
+			errorContains: "specified without glob pattern",
+		},
+		{
+			name:        "directory with glob pattern should skip",
+			source:      testDir,
+			matches:     []string{testDir + "/file1.txt", testDir + "/file2.txt"},
+			expectError: false,
+			expectSkip:  true,
+		},
+		{
+			name:        "non-existent path should skip",
+			source:      "/non/existent/path", 
+			matches:     []string{},
+			expectError: false,
+			expectSkip:  true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			err := isDir(tc.source, tc.matches)
+			
+			if tc.expectError {
+				if err == nil {
+					t.Errorf("Expected error but got none")
+				} else if err == errSkip {
+					t.Errorf("Expected fatal error but got skip error")
+				} else if tc.errorContains != "" && !strings.Contains(err.Error(), tc.errorContains) {
+					t.Errorf("Expected error to contain '%s', but got: %v", tc.errorContains, err)
+				}
+			} else if tc.expectSkip {
+				if err != errSkip {
+					t.Errorf("Expected skip error but got: %v", err)
+				}
+			} else {
+				if err != nil {
+					t.Errorf("Expected no error but got: %v", err)
+				}
+			}
+		})
+	}
+}
\ No newline at end of file
diff --git a/plugin_unix_test.go b/plugin_unix_test.go
index 336080d..cdf8415 100644
--- a/plugin_unix_test.go
+++ b/plugin_unix_test.go
@@ -128,3 +128,4 @@ func TestResolveSource(t *testing.T) {
 		}
 	}
 }
+