diff --git a/src/runtime/haskell-bind/PGF2.hsc b/src/runtime/haskell-bind/PGF2.hsc
index 4b41a7471..cdb4a7994 100644
--- a/src/runtime/haskell-bind/PGF2.hsc
+++ b/src/runtime/haskell-bind/PGF2.hsc
@@ -1266,7 +1266,9 @@ withBracketLinFuncs ref exn f =
         then writeIORef ref (stack, bs')
         else do cat <- peekUtf8CString c_cat
                 let fid    = fromIntegral c_fid
-                ann <- peekUtf8CString c_ann
+                ann <- if c_ann == nullPtr
+                         then return ""
+                         else peekUtf8CString c_ann
                 fun <- peekUtf8CString c_fun
                 writeIORef ref (stack, Bracket cat fid ann fun (reverse bs) : bs')