diff --git a/graph b/graph
index 786096c..d62b2b6 100755
--- a/graph
+++ b/graph
@@ -125,7 +125,7 @@ else
 	cat <<-EOHEAD
 		content-type: image/png
 		Last-Modified: $(LC_ALL=C TZ=GMT date +'%a, %d %b %Y %X %Z')
-		Expires: $(LC_ALL=C TZ=GMT date +'%a, %d %b %Y %X %Z' -d '10 minutes')
+		Expires: $(LC_ALL=C TZ=GMT date +'%a, %d %b %Y %X %Z' -d '1 hour')
 		Cache-Control: max-age=0, must-revalidate
 
 	EOHEAD