diff --git a/lib/kafs/afssysdefs.h b/lib/kafs/afssysdefs.h
index 5c593be93..5c6f93b5a 100644
--- a/lib/kafs/afssysdefs.h
+++ b/lib/kafs/afssysdefs.h
@@ -31,6 +31,10 @@
 #define AFS_SYSCALL2	258
 #endif
 
+#if defined(__ultrix)
+#define AFS_SYSCALL	31
+#endif
+
 #if defined(__linux)
 /* Kent Engström <kent@lysator.liu.se> 1995-08-22
    Linux has no SIGSYS signal. Furthermore, the normal