diff --git a/glib/tests/cxx.cpp b/glib/tests/cxx.cpp
index 8c31f7380..243134009 100644
--- a/glib/tests/cxx.cpp
+++ b/glib/tests/cxx.cpp
@@ -470,6 +470,7 @@ test_string_append (void)
   g_assert_cmpstr (string->str, ==, "firsthalflasthalfmoreore");
 
   g_string_free (string, TRUE);
+  g_free (tmp);
 }
 
 static void