diff --git a/ipc/compat.c b/ipc/compat.c
index f71e962..f486b00 100644
--- a/ipc/compat.c
+++ b/ipc/compat.c
@@ -381,7 +381,7 @@
 			uptr = compat_ptr(ipck.msgp);
 			fifth = ipck.msgtyp;
 		}
-		return do_msgrcv(first, uptr, second, fifth, third,
+		return do_msgrcv(first, uptr, second, (s32)fifth, third,
 				 compat_do_msg_fill);
 	}
 	case MSGGET: