diff --git a/tests/gmap.v b/tests/gmap.v
index 3eb98b0619ee09a6c29f59acc8ce10f4e8afb1b2..fff2df33a33d84a01b1ac8737b2974b467a1365d 100644
--- a/tests/gmap.v
+++ b/tests/gmap.v
@@ -82,3 +82,10 @@ Proof.
   Fail progress simplify_eq.
   done.
 Qed.
+
+(** Test case for issue #139 *)
+
+Lemma test_issue_139 (m : gmap nat nat) : ∃ x, x ∉ dom m.
+Proof.
+  destruct (exist_fresh (dom m)); eauto.
+Qed.