diff --git a/shared/nm-utils/nm-test-utils.h b/shared/nm-utils/nm-test-utils.h
index 6c945b1920..a6a5c5d171 100644
--- a/shared/nm-utils/nm-test-utils.h
+++ b/shared/nm-utils/nm-test-utils.h
@@ -1143,6 +1143,13 @@ nmtst_g_source_assert_not_called(gpointer user_data)
     return G_SOURCE_CONTINUE;
 }
 
+static inline gboolean
+nmtst_g_source_nop(gpointer user_data)
+{
+    g_assert(!user_data);
+    return G_SOURCE_CONTINUE;
+}
+
 static inline gboolean
 nmtst_g_source_set_boolean_true(gpointer user_data)
 {