diff --git a/lib/chai/core/assertions.js b/lib/chai/core/assertions.js
index 072718e86..ae847d0e4 100644
--- a/lib/chai/core/assertions.js
+++ b/lib/chai/core/assertions.js
@@ -1565,6 +1565,7 @@ module.exports = function (chai, _) {
         , 'expected #{this} to not be a superset of #{act}'
         , obj
         , subset
+        , true
       );
     }
 
@@ -1574,6 +1575,7 @@ module.exports = function (chai, _) {
         , 'expected #{this} to not have the same members as #{act}'
         , obj
         , subset
+        , true
     );
   });