diff --git a/install.sh b/install.sh
index 1930a25..ccfec9e 100755
--- a/install.sh
+++ b/install.sh
@@ -364,7 +364,7 @@ then
         echo "Disabling compress.cache-dir in /etc/lighttpd/lighttpd.conf due to often causing full disk issues when compression for filetype application/json is enabled."
         echo -----
         sed -i -e 's$^compress.cache-dir.*$#\0 # disabled by tar1090, often causes full disk$' /etc/lighttpd/lighttpd.conf
-    else
+    elif ! grep -qs -e 'full disk when using tar1090' /etc/lighttpd/lighttpd.conf; then
         sed -i -e 's$^compress.cache-dir.*$# CAUTION, enabling cache-dir and filetype json will cause full disk when using tar1090\n\0$' /etc/lighttpd/lighttpd.conf
     fi
 fi