diff --git a/sh/xkcd b/sh/xkcd
index c48302c..dc8179c 100755
--- a/sh/xkcd
+++ b/sh/xkcd
@@ -1,6 +1,6 @@
 #!/bin/sh
 
-set -x
+[ -z $XKCD_DBG ] || set -x
 err () {
   printf "err: %s\n" ${1}
   [ -z "${2}" ] && exit 1