diff --git a/hnix-store-readonly/hnix-store-readonly.cabal b/hnix-store-readonly/hnix-store-readonly.cabal
index 9ca79484..ae4c6d3e 100644
--- a/hnix-store-readonly/hnix-store-readonly.cabal
+++ b/hnix-store-readonly/hnix-store-readonly.cabal
@@ -59,5 +59,6 @@ test-suite readonly
     , bytestring
     , crypton
     , data-default-class
+    , dependent-sum
     , hspec
     , unordered-containers
diff --git a/hnix-store-readonly/tests/ReadOnlySpec.hs b/hnix-store-readonly/tests/ReadOnlySpec.hs
index 6d449672..00c302ec 100644
--- a/hnix-store-readonly/tests/ReadOnlySpec.hs
+++ b/hnix-store-readonly/tests/ReadOnlySpec.hs
@@ -7,6 +7,8 @@ import Test.Hspec (Spec, describe, it, shouldBe, pendingWith)
 
 import Crypto.Hash (hash, Digest, SHA256(..))
 import Data.ByteString (ByteString)
+import Data.Dependent.Sum (DSum(..))
+import System.Nix.Hash (HashAlgo(..))
 import System.Nix.StorePath (StorePath, StorePathName)
 import System.Nix.Store.Types (FileIngestionMethod(..))
 
@@ -18,6 +20,9 @@ import System.Nix.Store.ReadOnly
 testDigest :: Digest SHA256
 testDigest = Crypto.Hash.hash @ByteString "testDigest"
 
+testDigest' :: DSum HashAlgo Digest
+testDigest' = HashAlgo_SHA256 :=> testDigest
+
 testName :: StorePathName
 testName =
     either undefined id
@@ -45,7 +50,7 @@ spec = do
         $ makeStorePath
             def
             "test"
-            testDigest
+            testDigest'
             testName
       )
       `shouldBe`
@@ -86,7 +91,7 @@ spec = do
           $ makeFixedOutputPath
               def
               FileIngestionMethod_FileRecursive
-              testDigest
+              testDigest'
               testName
         )
         `shouldBe`
@@ -99,7 +104,7 @@ spec = do
           $ makeFixedOutputPath
               def
               FileIngestionMethod_Flat
-              testDigest
+              testDigest'
               testName
         )
         `shouldBe`