diff --git a/src/testing.c b/src/testing.c
index 675eaa2..4e688a7 100644
--- a/src/testing.c
+++ b/src/testing.c
@@ -1153,7 +1153,10 @@
 {
     // This is dangerous, any Lists and Dicts used internally may be freed
     // while still in use.
-    garbage_collect(TRUE);
+    if (!get_vim_var_nr(VV_TESTING))
+	emsg(_(e_calling_test_garbagecollect_now_while_v_testing_is_not_set));
+    else
+	garbage_collect(TRUE);
 }
 
 /*