diff --git a/isisd/isis_zebra.c b/isisd/isis_zebra.c
index 6c398cf..a1a5bea 100644
--- a/isisd/isis_zebra.c
+++ b/isisd/isis_zebra.c
@@ -541,7 +541,7 @@
   api.message = stream_getc (stream);
 
   p.family = AF_INET;
-  p.prefixlen = stream_getc (stream);
+  p.prefixlen = MIN(IPV4_MAX_PREFIXLEN, stream_getc (stream));
   stream_get (&p.prefix, stream, PSIZE (p.prefixlen));
 
   if (CHECK_FLAG (api.message, ZAPI_MESSAGE_NEXTHOP))