diff --git a/servant/servant.cabal b/servant/servant.cabal
index 3e126d66..1f4f9fa7 100644
--- a/servant/servant.cabal
+++ b/servant/servant.cabal
@@ -66,7 +66,7 @@ library
     , http-types            >= 0.8  && < 0.10
     , natural-transformation >= 0.4 && < 0.5
     , mtl                   >= 2.0  && < 2.3
-    , mmorph                >= 1    && < 1.1
+    , mmorph                >= 1    && < 1.2
     , tagged                >= 0.7.3 && < 0.9
     , text                  >= 1    && < 1.3
     , string-conversions    >= 0.3  && < 0.5