diff --git a/src/testing.c b/src/testing.c
index 0971876..ed2d511 100644
--- a/src/testing.c
+++ b/src/testing.c
@@ -615,7 +615,8 @@
 	    goto theend;
 	}
 
-	if (!error_found && argvars[3].v_type == VAR_NUMBER
+	if (!error_found && argvars[2].v_type != VAR_UNKNOWN
+		&& argvars[3].v_type == VAR_NUMBER
 		&& argvars[3].vval.v_number >= 0
 		&& argvars[3].vval.v_number != emsg_assert_fails_lnum)
 	{