diff --git a/winsup/cygserver/ChangeLog b/winsup/cygserver/ChangeLog
index f32817e69..5a87a67b6 100644
--- a/winsup/cygserver/ChangeLog
+++ b/winsup/cygserver/ChangeLog
@@ -1,3 +1,9 @@
+2003-11-22  Corinna Vinschen  <corinna@vinschen.de>
+
+	* msg.cc (client_request_msg::serve): Add default case to msgop switch.
+	* sem.cc (client_request_sem::serve): Add default case to semop switch.
+	* shm.cc (client_request_shm::serve): Add default case to shmop switch.
+
 2003-11-21  Corinna Vinschen  <corinna@vinschen.de>
 
 	* Makefile.in (install): Explicitely create directories.  Install
diff --git a/winsup/cygserver/msg.cc b/winsup/cygserver/msg.cc
index 713a5866a..52fdcd07e 100644
--- a/winsup/cygserver/msg.cc
+++ b/winsup/cygserver/msg.cc
@@ -95,6 +95,10 @@ client_request_msg::serve (transport_layer_base *const conn,
       case MSGOP_msgsnd:
 	res = msgsnd (&td, &_parameters.in.sndargs);
         break;
+      default:
+	res = ENOSYS;
+        td.td_retval[0] = -1;
+	break;
     }
   /* Allocated by the call to adjust_identity_info(). */
   if (_parameters.in.ipcblk.gidlist)
diff --git a/winsup/cygserver/sem.cc b/winsup/cygserver/sem.cc
index 6a179b0b6..dd48123d2 100644
--- a/winsup/cygserver/sem.cc
+++ b/winsup/cygserver/sem.cc
@@ -89,6 +89,10 @@ client_request_sem::serve (transport_layer_base *const conn,
       case SEMOP_semop:
 	res = semop (&td, &_parameters.in.opargs);
         break;
+      default:
+	res = ENOSYS;
+        td.td_retval[0] = -1;
+	break;
     }
   /* Allocated by the call to adjust_identity_info(). */
   if (_parameters.in.ipcblk.gidlist)
diff --git a/winsup/cygserver/shm.cc b/winsup/cygserver/shm.cc
index f73fd012a..d8284cd44 100644
--- a/winsup/cygserver/shm.cc
+++ b/winsup/cygserver/shm.cc
@@ -101,6 +101,10 @@ client_request_shm::serve (transport_layer_base *const conn,
       case SHMOP_shmfork:
         res = cygwin_shmfork_myhook (&td, &_parameters.in.forkargs);
 	break;
+      default:
+	res = ENOSYS;
+        td.td_retval[0] = -1;
+	break;
     }
   /* Allocated by the call to adjust_identity_info(). */
   if (_parameters.in.ipcblk.gidlist)