diff --git a/sys/i386/ibcs2/syscalls.isc b/sys/i386/ibcs2/syscalls.isc
index abf0b1897424..71ae5dc2a046 100644
--- a/sys/i386/ibcs2/syscalls.isc
+++ b/sys/i386/ibcs2/syscalls.isc
@@ -14,7 +14,7 @@
 3	AUE_NULL	MNOPROTO	{ int ibcs2_sigaction(int sig, \
 				    struct ibcs2_sigaction *act, \
 				    struct ibcs2_sigaction *oact); }
-4	AUE_NULL	NOPROTO	{ int ibcs2_sigprocmask(int how, \
+4	AUE_NULL	MNOPROTO	{ int ibcs2_sigprocmask(int how, \
 				    ibcs2_sigset_t *set, \
 				    ibcs2_sigset_t *oset); }
 5	AUE_NULL	MNOPROTO	{ int ibcs2_sigpending(ibcs2_sigset_t *mask); }