diff --git a/src/Refinements-Tests/FQPosTest.class.st b/src/Refinements-Tests/FQPosTest.class.st
index bdc3f3d22..09247ae10 100644
--- a/src/Refinements-Tests/FQPosTest.class.st
+++ b/src/Refinements-Tests/FQPosTest.class.st
@@ -31,3 +31,24 @@ constraint:
   tag [1]
 '
 ]
+
+{ #category : #tests }
+FQPosTest >> testEqConstr1 [
+	self provePos: '
+data Thing 0 = [
+  | Cons {Head : int}
+]
+
+bind 0 a : {v: Thing | Bool true }
+bind 1 x : {v: Thing | Bool true }
+bind 2 y : {v: `a    | Bool true }
+
+constraint:
+  env [0; 1; 2]
+  lhs {v:int | x === y }
+  rhs {v:int | y === x }
+  id 1 tag []
+'.
+
+
+]