diff --git a/src/Database/LSMTree/Internal/ChecksumHandle.hs b/src/Database/LSMTree/Internal/ChecksumHandle.hs
index 55d8e95b0..3956934a0 100644
--- a/src/Database/LSMTree/Internal/ChecksumHandle.hs
+++ b/src/Database/LSMTree/Internal/ChecksumHandle.hs
@@ -209,13 +209,13 @@ writeFilter hfs filterHandle bf =
 {-# SPECIALISE writeIndexHeader ::
      HasFS IO h
   -> ForIndex (ChecksumHandle RealWorld h)
-  -> Proxy# i
+  -> IndexType
   -> IO () #-}
 writeIndexHeader ::
      (MonadSTM m, PrimMonad m)
   => HasFS m h
   -> ForIndex (ChecksumHandle (PrimState m) h)
-  -> Proxy# i
+  -> IndexType
   -> m ()
 writeIndexHeader hfs indexHandle indexTypeProxy =
     writeToHandle hfs (unForIndex indexHandle) $
diff --git a/src/Database/LSMTree/Internal/Config.hs b/src/Database/LSMTree/Internal/Config.hs
index bcd758fd5..6eb4b8d0c 100644
--- a/src/Database/LSMTree/Internal/Config.hs
+++ b/src/Database/LSMTree/Internal/Config.hs
@@ -319,13 +319,13 @@ instance NFData FencePointerIndex where
   rnf OrdinaryIndex = ()
 
 withIndexTypeProxyForRun :: FencePointerIndex
-                         -> (forall i . Index i => Proxy# i -> r)
+                         -> (forall i . Index i => IndexType -> r)
                          -> r
 withIndexTypeProxyForRun CompactIndex  cont = cont (proxy# @IndexCompact)
 withIndexTypeProxyForRun OrdinaryIndex cont = cont (proxy# @IndexOrdinary)
 
 withIndexAccTypeProxyForRun :: FencePointerIndex
-                            -> (forall j . IndexAcc j => Proxy# j -> r)
+                            -> (forall j . IndexAcc j => IndexType -> r)
                             -> r
 withIndexAccTypeProxyForRun CompactIndex  cont = cont (proxy# @IndexCompactAcc)
 withIndexAccTypeProxyForRun OrdinaryIndex cont = cont (proxy# @IndexOrdinaryAcc)
diff --git a/src/Database/LSMTree/Internal/Merge.hs b/src/Database/LSMTree/Internal/Merge.hs
index 0eec4e5da..3707ee2e5 100644
--- a/src/Database/LSMTree/Internal/Merge.hs
+++ b/src/Database/LSMTree/Internal/Merge.hs
@@ -90,7 +90,7 @@ type Mappend = SerialisedValue -> SerialisedValue -> SerialisedValue
   -> HasBlockIO IO h
   -> RunDataCaching
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> Level
   -> Mappend
   -> Run.RunFsPaths
@@ -104,7 +104,7 @@ new ::
   -> HasBlockIO m h
   -> RunDataCaching
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> Level
   -> Mappend
   -> Run.RunFsPaths
diff --git a/src/Database/LSMTree/Internal/MergingRun.hs b/src/Database/LSMTree/Internal/MergingRun.hs
index 57c633f02..dfefbeb4f 100644
--- a/src/Database/LSMTree/Internal/MergingRun.hs
+++ b/src/Database/LSMTree/Internal/MergingRun.hs
@@ -118,7 +118,7 @@ instance NFData MergeKnownCompleted where
   -> ResolveSerialisedValue
   -> Run.RunDataCaching
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> Merge.Level
   -> RunFsPaths
   -> V.Vector (Ref (Run IO h))
@@ -137,7 +137,7 @@ new ::
   -> ResolveSerialisedValue
   -> Run.RunDataCaching
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> Merge.Level
   -> RunFsPaths
   -> V.Vector (Ref (Run m h))
diff --git a/src/Database/LSMTree/Internal/Run.hs b/src/Database/LSMTree/Internal/Run.hs
index 8cf14b251..47a51a7e9 100644
--- a/src/Database/LSMTree/Internal/Run.hs
+++ b/src/Database/LSMTree/Internal/Run.hs
@@ -205,7 +205,7 @@ fromMutable runRunDataCaching builder = do
   -> HasBlockIO IO h
   -> RunDataCaching
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> RunFsPaths
   -> WriteBuffer
   -> Ref (WriteBufferBlobs IO h)
@@ -223,7 +223,7 @@ fromWriteBuffer ::
   -> HasBlockIO m h
   -> RunDataCaching
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> RunFsPaths
   -> WriteBuffer
   -> Ref (WriteBufferBlobs m h)
@@ -256,7 +256,7 @@ data FileFormatError = FileFormatError FS.FsPath String
      HasFS IO h
   -> HasBlockIO IO h
   -> RunDataCaching
-  -> Proxy# i
+  -> IndexType
   -> RunFsPaths
   -> IO (Ref (Run IO h)) #-}
 -- | Load a previously written run from disk, checking each file's checksum
@@ -272,7 +272,7 @@ openFromDisk ::
   => HasFS m h
   -> HasBlockIO m h
   -> RunDataCaching
-  -> Proxy# i
+  -> IndexType
   -> RunFsPaths
   -> m (Ref (Run m h))
 openFromDisk fs hbio runRunDataCaching indexTypeProxy runRunFsPaths = do
diff --git a/src/Database/LSMTree/Internal/RunAcc.hs b/src/Database/LSMTree/Internal/RunAcc.hs
index b8c9b4b13..21f94fb51 100644
--- a/src/Database/LSMTree/Internal/RunAcc.hs
+++ b/src/Database/LSMTree/Internal/RunAcc.hs
@@ -93,7 +93,7 @@ data RunBloomFilterAlloc =
 -- output run.
 new :: NumEntries
     -> RunBloomFilterAlloc
-    -> Proxy# j
+    -> IndexType
     -> ST s (RunAcc s)
 new (NumEntries nentries) alloc indexAccTypeProxy = do
     mbloom <- case alloc of
diff --git a/src/Database/LSMTree/Internal/RunBuilder.hs b/src/Database/LSMTree/Internal/RunBuilder.hs
index 83cd69984..500ecfd8e 100644
--- a/src/Database/LSMTree/Internal/RunBuilder.hs
+++ b/src/Database/LSMTree/Internal/RunBuilder.hs
@@ -76,7 +76,7 @@ data RunBuilder m h = RunBuilder {
   -> RunFsPaths
   -> NumEntries
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> IO (RunBuilder IO h) #-}
 -- | Create an 'RunBuilder' to start building a run.
 --
@@ -88,7 +88,7 @@ new ::
   -> RunFsPaths
   -> NumEntries  -- ^ an upper bound of the number of entries to be added
   -> RunBloomFilterAlloc
-  -> Proxy# j
+  -> IndexType
   -> m (RunBuilder m h)
 new hfs hbio runBuilderFsPaths numEntries alloc indexAccTypeProxy = do
     runBuilderAcc <- ST.stToIO $ RunAcc.new numEntries alloc indexAccTypeProxy