Index: ghc-8.6.1/libraries/ghc-heap/GHC/Exts/Heap/InfoTable.hsc
===================================================================
--- ghc-8.6.1.orig/libraries/ghc-heap/GHC/Exts/Heap/InfoTable.hsc
+++ ghc-8.6.1/libraries/ghc-heap/GHC/Exts/Heap/InfoTable.hsc
@@ -58,7 +58,7 @@ pokeItbl a0 itbl = do
 #endif
   (#poke StgInfoTable, layout.payload.ptrs) a0 (ptrs itbl)
   (#poke StgInfoTable, layout.payload.nptrs) a0 (nptrs itbl)
-  (#poke StgInfoTable, type) a0 (fromEnum (tipe itbl))
+  (#poke StgInfoTable, type) a0 (toHalfWord (fromEnum (tipe itbl)))
 #if __GLASGOW_HASKELL__ > 804
   (#poke StgInfoTable, srt) a0 (srtlen itbl)
 #else
@@ -71,6 +71,9 @@ pokeItbl a0 itbl = do
     Just (Left xs) -> pokeArray code_offset xs
     Just (Right xs) -> pokeArray code_offset xs
 #endif
+  where
+    toHalfWord :: Int -> HalfWord
+    toHalfWord i = fromIntegral i
 
 -- | Size in bytes of a standard InfoTable
 itblSize :: Int