diff --git a/changelog.md b/changelog.md
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,11 @@
 # Hashtables changelog
 
+## 1.3.1
+
+Fix Noncanonical mappend definition warning.
+Support more recent compilers.
+
+
 ## 1.3
 
 Support Hashable 1.4. This new version of Hashable drops the Eq constraint, so the Eq constraint
diff --git a/hashtables.cabal b/hashtables.cabal
--- a/hashtables.cabal
+++ b/hashtables.cabal
@@ -1,6 +1,6 @@
 Cabal-Version: 2.2
 Name:                hashtables
-Version:             1.3
+Version:             1.3.1
 Synopsis:            Mutable hash tables in the ST monad
 Homepage:            http://github.com/gregorycollins/hashtables
 License:             BSD-3-Clause
@@ -22,7 +22,8 @@
   GHC == 8.8.4
   GHC == 8.10.7
   GHC == 9.0.1
-  GHC == 9.2.1
+  GHC == 9.2.4
+  GHC == 9.4.2
 
 Description:
   This package provides a couple of different implementations of mutable hash
@@ -194,7 +195,7 @@
   Build-depends:     base      >= 4.7 && <5,
                      hashable  >= 1.4 && < 1.5,
                      primitive,
-                     vector    >= 0.7 && <0.13
+                     vector    >= 0.7 && <0.14
 
   if flag(portable)
     cpp-options: -DNO_C_SEARCH -DPORTABLE
diff --git a/src/Data/HashTable/ST/Basic.hs b/src/Data/HashTable/ST/Basic.hs
--- a/src/Data/HashTable/ST/Basic.hs
+++ b/src/Data/HashTable/ST/Basic.hs
@@ -519,15 +519,19 @@
 
 #if MIN_VERSION_base(4,9,0)
 instance Semigroup Slot where
- (<>) = mappend
+  (<>) = slotMappend
 #endif
 
 instance Monoid Slot where
-    mempty = Slot maxBound
-    (Slot x1) `mappend` (Slot x2) =
-        let !m = mask x1 maxBound
-        in Slot $! (complement m .&. x1) .|. (m .&. x2)
+  mempty = Slot maxBound
+#if ! MIN_VERSION_base(4,11,0)
+  mappend = slotMappend
+#endif
 
+slotMappend :: Slot -> Slot -> Slot
+slotMappend (Slot x1) (Slot x2) =
+  let !m = mask x1 maxBound
+  in Slot $! (complement m .&. x1) .|. (m .&. x2)
 
 ------------------------------------------------------------------------------
 -- findSafeSlots return type
@@ -841,3 +845,4 @@
                 let !i' = fromIntegral i
                 return (Just (i', k, v))
 {-# INLINE nextByIndex #-}
+