diff --git a/test/SpecCHK.hs b/test/SpecCHK.hs
index efd8790837689ba5559c1ad4ab54144234f91cd5..5b6294809fb9f7d68dd0693f6c52429b488af62f 100644
--- a/test/SpecCHK.hs
+++ b/test/SpecCHK.hs
@@ -355,8 +355,11 @@ prop_decrypt_segmentSize_invariant = property $ do
 
     ciphertext <- liftIO $ getCiphertext key plaintext 16
 
-    let plaintextA = B.concat $ zipWith (curry $ decryptSegment' key) [0, fromIntegral segmentSizeA `div` 16 ..] (chunkedBy segmentSizeA ciphertext)
-        plaintextB = B.concat $ zipWith (curry $ decryptSegment' key) [0, fromIntegral segmentSizeB `div` 16 ..] (chunkedBy segmentSizeB ciphertext)
+    let decrypt segmentSize =
+            B.concat $ zipWith (curry $ decryptSegment' key) [0, fromIntegral segmentSize ..] (chunkedBy segmentSize ciphertext)
+        plaintextA = decrypt segmentSizeA
+        plaintextB = decrypt segmentSizeB
+
     diff plaintextA (==) plaintextB
 
 prop_encrypt_decrypt_roundtrip :: Property