Fix 64 bits compilation warnings

1 files changed, 2 insertions, 2 deletions

diff --git a/src/lanes.c b/src/lanes.c
index 2cb1af8..ef08e3a 100644
--- a/src/lanes.c
+++ b/src/lanes.c
@@ -413,11 +413,11 @@ struct s_Linda
         SIGNAL_T read_happened;
         SIGNAL_T write_happened;
         struct s_Universe* U; // the universe this linda belongs to
+        ptrdiff_t group; // a group to control keeper allocation between lindas
         enum e_cancel_request simulate_cancel;
-        unsigned long group; // a group to control keeper allocation between lindas
         char name[1];
 };
-#define LINDA_KEEPER_HASHSEED( linda) (linda->group ? linda->group : (unsigned long)linda)
+#define LINDA_KEEPER_HASHSEED( linda) (linda->group ? linda->group : (ptrdiff_t)linda)
 
 static void* linda_id( lua_State*, enum eDeepOp);