diff --git a/filter/f-inst.c b/filter/f-inst.c
index 3fea16c4..d6c292b6 100644
--- a/filter/f-inst.c
+++ b/filter/f-inst.c
@@ -233,7 +233,7 @@
     ARG_ANY(1);
     ARG_ANY(2);
     int i = val_in_range(&v1, &v2);
-    if (res.val.i == F_CMP_ERROR)
+    if (i == F_CMP_ERROR)
       runtime( "!~ applied on unknown type pair" );
     RESULT(T_BOOL, i, !i);
   }
diff --git a/filter/test.conf b/filter/test.conf
index b9f1b3aa..ba25a34b 100644
--- a/filter/test.conf
+++ b/filter/test.conf
@@ -136,6 +136,7 @@ int set is;
 	bt_assert(2 ~ [ 1, 2, 3 ]);
 	bt_assert(5 ~ [ 4 .. 7 ]);
 	bt_assert(1 !~ [ 2, 3, 4 ]);
+	bt_assert(999 !~ [ 666, 333 ]);
 
 	is = [ 2, 3, 4, 7..11 ];
 	bt_assert(10 ~ is);