--- a/js/xpconnect/src/XPCWrappedNative.cpp
+++ b/js/xpconnect/src/XPCWrappedNative.cpp
@@ -2850,17 +2850,18 @@ CallMethodHelper::CleanupParam(nsXPTCMin
         case nsXPTType::T_DOMSTRING:
             mCallContext.DeleteString((nsAString*)param.val.p);
             break;
         case nsXPTType::T_UTF8STRING:
         case nsXPTType::T_CSTRING:
             delete (nsCString*) param.val.p;
             break;
         default:
-            NS_ABORT_IF_FALSE(type.IsPointer(), "Cleanup requested on unexpected type.");
+            NS_ABORT_IF_FALSE(!type.IsArithmetic(),
+                              "Cleanup requested on unexpected type.");
             nsMemory::Free(param.val.p);
             break;
     }
 }
 
 // Handle parameters with dipper types.
 //
 // Dipper types are one of the more inscrutable aspects of xpidl. In a