1 files changed, 1 insertions, 0 deletions

diff --git a/src/syssignal.h b/src/syssignal.h
index 40deead0fbe..432eb163322 100644
--- a/src/syssignal.h
+++ b/src/syssignal.h
@@ -43,6 +43,7 @@ extern sigset_t empty_mask, full_mask, temp_mask;
     _mask;                                      \
   })
 #else /* ! defined (__GNUC__) */
+extern sigset_t sys_sigmask ();
 #define sigmask(SIG) (sys_sigmask (SIG))
 #endif /* ! defined (__GNUC__) */
 #endif