diff --git a/numbers.c b/numbers.c
index 5c2f30a..1fdae3f 100644
--- a/numbers.c
+++ b/numbers.c
@@ -71,21 +71,24 @@ unsigned int *createNumbers(unsigned int len) {
 // on errors.
 unsigned int getDuplicate(const unsigned int *numbers, unsigned int len) {
   if (!numbers || len < 2)
-    return NULL; // Fehlerhaftes Array
+    return 0; // Sicherheit: kein Array oder zu kurz
 
-  TreeNode *root = NULL; // neuer Baum
+  TreeNode *root = NULL;
   unsigned int duplicateValue = 0;
 
   for (unsigned int i = 0; i < len; i++) {
     int isDuplicate = 0;
+
+    // Zahl in den Baum einfügen
     root = addToTree(root, &numbers[i], sizeof(unsigned int),
                      compareUnsignedInt, &isDuplicate);
-    if (isDuplicate) {
-      duplicateValue = numbers[i];
-      break;
+
+    // Duplikat erkannt
+    if (isDuplicate && duplicateValue == 0) {
+      duplicateValue = numbers[i]; // das erste Duplikat merken
     }
   }
 
-  clearTree(root);
-  return duplicateValue;
+  clearTree(root);       // Baum freigeben
+  return duplicateValue; // 0, falls kein Duplikat
 }