diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 1.6.1
+
+* Explicitly define `(<>)` in the `Semigroup` instance for `Enctype`
+
 ## 1.6.0
 
 * Upgrade to yesod-core 1.6.0
diff --git a/Yesod/Form/Types.hs b/Yesod/Form/Types.hs
--- a/Yesod/Form/Types.hs
+++ b/Yesod/Form/Types.hs
@@ -104,9 +104,12 @@
     toValue Multipart = "multipart/form-data"
 instance Monoid Enctype where
     mempty = UrlEncoded
-    mappend UrlEncoded UrlEncoded = UrlEncoded
-    mappend _ _ = Multipart
-instance Semigroup Enctype
+#if !(MIN_VERSION_base(4,11,0))
+    mappend = (<>)
+#endif
+instance Semigroup Enctype where
+    UrlEncoded <> UrlEncoded = UrlEncoded
+    _          <> _          = Multipart
 
 data Ints = IntCons Int Ints | IntSingle Int
 instance Show Ints where
diff --git a/yesod-form.cabal b/yesod-form.cabal
--- a/yesod-form.cabal
+++ b/yesod-form.cabal
@@ -1,5 +1,5 @@
 name:            yesod-form
-version:         1.6.0
+version:         1.6.1
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>