diff --git a/test/core/test_api.h b/test/core/test_api.h
index 74cab25..8135d5d 100644
--- a/test/core/test_api.h
+++ b/test/core/test_api.h
@@ -193,7 +193,7 @@ int test_core_api_object_cat_binary() {
 	for(int i = 0; i < 256; i++)
 		bytes[i] = i;
 	char* filename = "test1.txt";
-	create_file(filename, bytes, strlen((char*)bytes));
+	create_file(filename, bytes, 256);
 	struct HashtableNode* node;
 	size_t bytes_written;
 	struct IpfsNode *local_node = NULL;