diff --git a/nginx-cache-inspector b/nginx-cache-inspector
index 1a54bf7..edef3e3 100755
--- a/nginx-cache-inspector
+++ b/nginx-cache-inspector
@@ -37,7 +37,7 @@ function print_usage() {
 }
 
 ## Check the number of arguments.
-if [ $# -ne 2 ]; then
+if [ $# -ne 2 ] && [ $# -ne 3 ]; then
     print_usage
     exit 1
 fi
@@ -64,7 +64,7 @@ function get_cache_item_key() {
 ## Get a cache item TTL.
 ## $1 - cache file.
 function get_cache_item_ttl() {
-    od -dL $1 | sed -n '2p' | awk '{print $1 - $2}'
+    od -dL $1 | sed -n '4p' | awk '{print $2 - $1}'
 } # get_cache_item_ttl
 
 ## Inspects an item from the given cache zone.