gistfile1.txt

diff --git a/src/core/EnumMap.pm b/src/core/EnumMap.pm
index 4d28d09..e748ca4 100644
--- a/src/core/EnumMap.pm
+++ b/src/core/EnumMap.pm
@@ -75,10 +75,10 @@ my class EnumMap does Associative {
         }
     }

-    method at_key($key is copy) is rw {
-        $key = $key.Str;
-        self.exists($key)
-            ?? nqp::atkey($!storage, nqp::unbox_s($key))
+    method at_key($key) is rw {
+        my str $skey = nqp::unbox_s($key.Str);
+        nqp::defined($!storage) && nqp::existskye($!storage, $skey)
+            ?? nqp::atkey($!storage, $skey)
             !! Any
     }