diff --git a/test/completion/isinstance.py b/test/completion/isinstance.py
index f10d09f4..71011502 100644
--- a/test/completion/isinstance.py
+++ b/test/completion/isinstance.py
@@ -29,6 +29,14 @@ if 2:
     #? str()
     ass
 
+# -----------------
+# invalid arguments
+# -----------------
+
+if isinstance(wrong, str()):
+    #?
+    wrong
+
 # -----------------
 # in functions
 # -----------------