diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Revision history for futhark-data
 
+## 1.0.0.1 -- 2021-06-09
+
+* Fixed crash in value comparison.
+
 ## 1.0.0.0 -- 2021-06-08
 
 * First version. Released on an unsuspecting world.
diff --git a/futhark-data.cabal b/futhark-data.cabal
--- a/futhark-data.cabal
+++ b/futhark-data.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.4
 name:               futhark-data
-version:            1.0.0.0
+version:            1.0.0.1
 synopsis:           An implementation of the Futhark data format.
 
 description: The Futhark compiler and its tools uses a simple external
diff --git a/src/Futhark/Data/Compare.hs b/src/Futhark/Data/Compare.hs
--- a/src/Futhark/Data/Compare.hs
+++ b/src/Futhark/Data/Compare.hs
@@ -110,15 +110,16 @@
     [ArrayShapeMismatch i (valueShape got_v) (valueShape expected_v)]
   where
     unflatten = unflattenIndex (valueShape got_v)
-    value = undefined
+    value :: Show a => a -> T.Text
+    value = T.pack . show
     {-# INLINE compareGen #-}
     {-# INLINE compareNum #-}
     {-# INLINE compareFloat #-}
     {-# INLINE compareFloatElement #-}
     {-# INLINE compareElement #-}
-    compareNum :: (SVec.Storable a, Eq a) => SVec.Vector a -> SVec.Vector a -> [Mismatch]
+    compareNum :: (SVec.Storable a, Eq a, Show a) => SVec.Vector a -> SVec.Vector a -> [Mismatch]
     compareNum = compareGen compareElement
-    compareFloat :: (SVec.Storable a, RealFloat a) => a -> SVec.Vector a -> SVec.Vector a -> [Mismatch]
+    compareFloat :: (SVec.Storable a, RealFloat a, Show a) => a -> SVec.Vector a -> SVec.Vector a -> [Mismatch]
     compareFloat = compareGen . compareFloatElement
 
     compareGen cmp got expected =
@@ -134,12 +135,12 @@
               acc
        in reverse $ check [] 0
 
-    compareElement :: Eq a => Int -> a -> a -> Maybe Mismatch
+    compareElement :: (Show a, Eq a) => Int -> a -> a -> Maybe Mismatch
     compareElement j got expected
       | got == expected = Nothing
       | otherwise = Just $ PrimValueMismatch i (unflatten j) (value got) (value expected)
 
-    compareFloatElement :: RealFloat a => a -> Int -> a -> a -> Maybe Mismatch
+    compareFloatElement :: (Show a, RealFloat a) => a -> Int -> a -> a -> Maybe Mismatch
     compareFloatElement abstol j got expected
       | isNaN got,
         isNaN expected =