diff --git a/unordered-containers.cabal b/unordered-containers.cabal
index 37f5ba55..c1054102 100644
--- a/unordered-containers.cabal
+++ b/unordered-containers.cabal
@@ -42,13 +42,13 @@ flag debug
   description:  Enable debug support
   default:      False
 
-flag noSse42
+flag sse42
   description: Instruct GHC to *not* use -msse4.2. Typical use case is to allow
                older architectures to use unordered-containers. Only relevant
                for x86; expect performance regressions on newer architectures
                when enabled.
-  default:     False
-
+  default:     True
+  manual:      True
 
 library
   exposed-modules: