diff --git a/openbsc/src/libmgcp/mgcp_osmux.c b/openbsc/src/libmgcp/mgcp_osmux.c
index be0db99..b46a80e 100644
--- a/openbsc/src/libmgcp/mgcp_osmux.c
+++ b/openbsc/src/libmgcp/mgcp_osmux.c
@@ -543,7 +543,7 @@
 }
 
 /* bsc-nat allocates/releases the Osmux circuit ID */
-static uint8_t osmux_cid_bitmap[16];
+static uint8_t osmux_cid_bitmap[(OSMUX_CID_MAX + 1) / 8];
 
 int osmux_used_cid(void)
 {