diff --git a/sys/security/mac_biba/mac_biba.c b/sys/security/mac_biba/mac_biba.c
index 5d66e2fd4b9..120d2cdf997 100644
--- a/sys/security/mac_biba/mac_biba.c
+++ b/sys/security/mac_biba/mac_biba.c
@@ -112,7 +112,8 @@ SYSCTL_INT(_security_mac_biba, OID_AUTO, trust_all_interfaces, CTLFLAG_RDTUN,
 
 static char	trusted_interfaces[128];
 SYSCTL_STRING(_security_mac_biba, OID_AUTO, trusted_interfaces, CTLFLAG_RDTUN,
-    trusted_interfaces, 0, "Interfaces considered 'trusted' by MAC/Biba");
+    trusted_interfaces, sizeof(trusted_interfaces),
+    "Interfaces considered 'trusted' by MAC/Biba");
 
 static int	max_compartments = MAC_BIBA_MAX_COMPARTMENTS;
 SYSCTL_INT(_security_mac_biba, OID_AUTO, max_compartments, CTLFLAG_RD,
diff --git a/sys/security/mac_lomac/mac_lomac.c b/sys/security/mac_lomac/mac_lomac.c
index aa9abf45872..8fe13892bd3 100644
--- a/sys/security/mac_lomac/mac_lomac.c
+++ b/sys/security/mac_lomac/mac_lomac.c
@@ -113,7 +113,8 @@ SYSCTL_INT(_security_mac_lomac, OID_AUTO, trust_all_interfaces, CTLFLAG_RDTUN,
 
 static char	trusted_interfaces[128];
 SYSCTL_STRING(_security_mac_lomac, OID_AUTO, trusted_interfaces, CTLFLAG_RDTUN,
-    trusted_interfaces, 0, "Interfaces considered 'trusted' by MAC/LOMAC");
+    trusted_interfaces, sizeof(trusted_interfaces),
+    "Interfaces considered 'trusted' by MAC/LOMAC");
 
 static int	ptys_equal = 0;
 SYSCTL_INT(_security_mac_lomac, OID_AUTO, ptys_equal, CTLFLAG_RWTUN,