diff --git a/lib/des/rnd_keys.c b/lib/des/rnd_keys.c
index 4d6f4c089..96d17a026 100644
--- a/lib/des/rnd_keys.c
+++ b/lib/des/rnd_keys.c
@@ -182,6 +182,9 @@ sigALRM(int sig)
     if (igdata < gsize)
 	gdata[igdata++] ^= counter & 0xff;
 
+#ifndef HAVE_SIGACTION
+    signal(SIGALRM, sigALRM); /* Reinstall SysV signal handler */
+#endif
     SIGRETURN(0);
 }