diff --git a/mach/sun2/libsys/LIST b/mach/sun2/libsys/LIST
index 47351b70b..6597f0c64 100644
--- a/mach/sun2/libsys/LIST
+++ b/mach/sun2/libsys/LIST
@@ -135,6 +135,7 @@ signal.c
 sigpause.s
 _sigpause.s
 sigsetmask.s
+_sigsetmask.s
 sigstack.s
 sigtramp.s
 sigvec.c
diff --git a/mach/sun2/libsys/_sigsetmask.s b/mach/sun2/libsys/_sigsetmask.s
new file mode 100644
index 000000000..17a92ae7e
--- /dev/null
+++ b/mach/sun2/libsys/_sigsetmask.s
@@ -0,0 +1,4 @@
+#include "syscall.h"
+.sect .text; .sect .rom; .sect .data; .sect .bss; .sect .text
+.define __sigsetmask
+__sigsetmask: SYSTEM(SYS_sigsetmask)