diff --git a/versionup.pl b/versionup.pl
index 21cfab4..9f23d3a 100755
--- a/versionup.pl
+++ b/versionup.pl
@@ -1,5 +1,9 @@
 #!/usr/bin/perl -i.orig  
 
+# Edit a build.gradle file in-place to update plugins to a specific version
+# To update all subprojects, run:
+# ./versionup.pl */build.gradle
+
 # Plugins and their latest versions
 $plugins = {
 	'com.google.protobuf'	=> '0.8.0',