diff --git a/bintree.c b/bintree.c
index 2a33201..a662790 100644
--- a/bintree.c
+++ b/bintree.c
@@ -61,6 +61,8 @@ TreeNode *addToTree(TreeNode *root, const void *data, size_t dataSize, CompareFc
             root->right = addToTree(root->right, data, dataSize, compareFct, isDuplicate);
         }
     }
+
+    return root;
 }
 
 // Iterates over the tree given by root. Follows the usage of strtok. If tree is NULL,
diff --git a/numbers.c b/numbers.c
index 7eac651..a4afc9e 100644
--- a/numbers.c
+++ b/numbers.c
@@ -39,7 +39,7 @@ unsigned int *createNumbers(unsigned int len)
   for (int i = 1; i < len; i++)
   {
     number = rand() % (2 * len) + 1;
-    addToTree(numbers, &number, sizeof(int), compareFct, &isDuplicate);
+    numbers = (numbers, &number, sizeof(int), compareFct, &isDuplicate);
     if (isDuplicate == 1)
     {
       isDuplicate = 0;