diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,7 @@
+## 2.1.8.1
+
+* fix a bad Eq instance /= definition for Key when mpsGenetric=True
+
 ## 2.1.7
 
 * Support for GHC 8 [#556](https://github.com/yesodweb/persistent/issues/556)
diff --git a/Database/Persist/TH.hs b/Database/Persist/TH.hs
--- a/Database/Persist/TH.hs
+++ b/Database/Persist/TH.hs
@@ -766,9 +766,6 @@
                 x == y =
                     ($(return unKeyE) x) ==
                     ($(return unKeyE) y)
-                x /= y =
-                    ($(return unKeyE) x) ==
-                    ($(return unKeyE) y)
              instance Ord (BackendKey $(pure backendT)) => Ord (Key $(pure recordType)) where
                 compare x y = compare
                     ($(return unKeyE) x)
diff --git a/persistent-template.cabal b/persistent-template.cabal
--- a/persistent-template.cabal
+++ b/persistent-template.cabal
@@ -1,5 +1,5 @@
 name:            persistent-template
-version:         2.1.8
+version:         2.1.8.1
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>