diff --git a/servers/ext2/table.c b/servers/ext2/table.c
index 2ebfcbce2..af77d746b 100644
--- a/servers/ext2/table.c
+++ b/servers/ext2/table.c
@@ -46,5 +46,11 @@ int (*fs_call_vec[])(void) = {
     fs_rdlink,          /* 30  */
     fs_getdents,        /* 31  */
     fs_statvfs,		/* 32  */
+#if 0
     fs_readwrite,       /* 33  */
+    no_sys,
+#else
+    no_sys,
+    no_sys,
+#endif
 };
diff --git a/servers/iso9660fs/table.c b/servers/iso9660fs/table.c
index e6cb5d387..12ac2f79a 100644
--- a/servers/iso9660fs/table.c
+++ b/servers/iso9660fs/table.c
@@ -41,5 +41,11 @@ int (*fs_call_vec[])(void) = {
   no_sys,			/* 30: not used */
   fs_getdents,			/* 31 */
   fs_statvfs,			/* 32 */
-  fs_read			/* 33 */
+#if 0
+  fs_read,			/* 33 */
+  no_sys,
+#else
+  no_sys,
+  no_sys,
+#endif
 };
diff --git a/servers/mfs/table.c b/servers/mfs/table.c
index d54c91558..8d19c3b8a 100644
--- a/servers/mfs/table.c
+++ b/servers/mfs/table.c
@@ -44,6 +44,6 @@ int (*fs_call_vec[])(void) = {
         fs_rdlink,	    /* 30  */
         fs_getdents,	    /* 31  */
         fs_statvfs,         /* 32  */
-        fs_readwrite,       /* 33  */
+        no_sys,             /* 33  */		/* peek not supported */
 };