diff --git a/internal/model/commit_message.go b/internal/model/commit_message.go
index 22ed110..2d28a43 100644
--- a/internal/model/commit_message.go
+++ b/internal/model/commit_message.go
@@ -19,7 +19,7 @@ func CreateCommitMessageFrom(messageLines []string) *CommitMessage {
 }
 
 func (cm *CommitMessage) ValidateSubject() int {
-	currentSubjectLength := len(cm.Subject)
+	currentSubjectLength := len([]rune(cm.Subject))
 
 	if strings.HasPrefix(cm.Subject, "Merge ") {
 		return 0
diff --git a/internal/model/commit_message_test.go b/internal/model/commit_message_test.go
index 5b405ae..da532d7 100644
--- a/internal/model/commit_message_test.go
+++ b/internal/model/commit_message_test.go
@@ -66,6 +66,7 @@ func TestNewCommitMessage(t *testing.T) {
 			{"short subject line", 0},
 			{"Merge pull request commits are ignored because they can easily exceed 52 characters", 0},
 			{"Merge branch commits are also ignored..............................................", 0},
+			{"I am a commit containing an umlaut ü.................", 3},
 		}
 
 		for _, tc := range testcases {