diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog for the [`ghc-typelits-natnormalise`](http://hackage.haskell.org/package/ghc-typelits-natnormalise) package
 
+## 0.7.2 *March 9 2020*
+* Fixes [#44](https://github.com/clash-lang/ghc-typelits-natnormalise/issues/44) infinite loop due to boxed equality
+
 ## 0.7.1 *February 6th 2020*
 * Add support for GHC 8.10.1-alpha2
 * Fixes [#23](https://github.com/clash-lang/ghc-typelits-natnormalise/issues/23): Can't figure out `+` commutes in some contexts on GHC 8.6.3
diff --git a/ghc-typelits-natnormalise.cabal b/ghc-typelits-natnormalise.cabal
--- a/ghc-typelits-natnormalise.cabal
+++ b/ghc-typelits-natnormalise.cabal
@@ -1,5 +1,5 @@
 name:                ghc-typelits-natnormalise
-version:             0.7.1
+version:             0.7.2
 synopsis:            GHC typechecker plugin for types of kind GHC.TypeLits.Nat
 description:
   A type checker plugin for GHC that can solve /equalities/ and /inequalities/
diff --git a/src/GHC/TypeLits/Normalise.hs b/src/GHC/TypeLits/Normalise.hs
--- a/src/GHC/TypeLits/Normalise.hs
+++ b/src/GHC/TypeLits/Normalise.hs
@@ -183,7 +183,8 @@
 #if MIN_VERSION_ghc(8,6,0)
 import Plugins    (purePlugin)
 #endif
-import PrelNames  (knownNatClassName)
+import PrelNames  (hasKey, knownNatClassName)
+import PrelNames  (eqTyConKey, heqTyConKey)
 import TcEvidence (EvTerm (..))
 #if MIN_VERSION_ghc(8,6,0)
 import TcEvidence (evCast)
@@ -192,7 +193,7 @@
 import TcPluginM  (zonkCt)
 #endif
 import TcPluginM  (TcPluginM, tcPluginTrace, tcPluginIO)
-import Type       (Kind, PredType, eqType, mkTyVarTy)
+import Type       (Kind, PredType, eqType, mkTyVarTy, tyConAppTyCon_maybe)
 import TysWiredIn (typeNatKind)
 
 import Coercion   (CoercionHole, Role (..), mkUnivCo)
@@ -257,6 +258,11 @@
 isEqPrimPred = isEqPred
 #endif
 
+isEqPredClass :: PredType -> Bool
+isEqPredClass ty = case tyConAppTyCon_maybe ty of
+  Just tc -> tc `hasKey` eqTyConKey || tc `hasKey` heqTyConKey
+  _ -> False
+
 -- | To use the plugin, add
 --
 -- @
@@ -392,7 +398,7 @@
         , let ev = ctEvidence ct
               prd = ctEvPred ev
         , isGiven ev
-        , not $ (\p -> isEqPred p || isEqPrimPred p) prd
+        , not $ (\p -> isEqPred p || isEqPrimPred p || isEqPredClass p) prd
         ]
   in filter
       (\(_, (prd, _, _)) ->