diff --git a/.zshrc b/.zshrc
index c91f202..909b64b 100644
--- a/.zshrc
+++ b/.zshrc
@@ -60,7 +60,7 @@ alias grep='grep -n --color=auto'
 alias j='jobs'
 alias df='df -h'
 alias du='du -ch'
-alias lock='xscreensaver-command --lock'
+hash xscreensaver-command 2>/dev/null && alias lock='xscreensaver-command --lock'
 hash sqlmap 2>/dev/null && alias sqlmap='sqlmap --user-agent="Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)"'
 hash sqlmap 2>/dev/null && alias sqlmap-tor='sqlmap --tor --tor-type=SOCKS5'
 hash steam 2>/dev/null && alias steam='find ~/.steam/root/ \( -name "libgcc_s.so*" -o -name "libstdc++.so*" -o -name "libxcb.so*" \) -print -delete; steam'