diff --git a/core/inference/inference-tests.factor b/core/inference/inference-tests.factor
index 46d1049a11..dc037d4a59 100755
--- a/core/inference/inference-tests.factor
+++ b/core/inference/inference-tests.factor
@@ -547,3 +547,12 @@ ERROR: custom-error ;
 [ [ missing->r-check ] infer ] must-fail
 
 { 1 0 } [ [ ] map-children ] must-infer-as
+
+! Corner case
+[ [ [ f dup ] [ dup ] [ ] unfold ] infer ] must-fail
+
+[ [ [ f dup ] [ ] [ ] while ] infer ] must-fail
+
+: erg's-inference-bug ( -- ) f dup [ erg's-inference-bug ] when ; inline
+
+[ [ erg's-inference-bug ] infer ] must-fail