diff --git a/src/engine/jam.c b/src/engine/jam.c
index 8367a0462..29c26f89f 100644
--- a/src/engine/jam.c
+++ b/src/engine/jam.c
@@ -270,7 +270,7 @@ int main( int argc, char * * argv, char * * arg_environ )
     sigprocmask(SIG_BLOCK, &sigmask, NULL);
     sa.sa_flags = 0;
     sa.sa_handler = child_sig_handler;
-    /* sigemptyset(&sa.sa_mask); */
+    sigemptyset(&sa.sa_mask);
     sigaction(SIGCHLD, &sa, NULL);
     sigemptyset(&empty_sigmask);
 #endif