diff --git a/increment_version.sh b/increment_version.sh
index bdba2b4..ad77a4a 100755
--- a/increment_version.sh
+++ b/increment_version.sh
@@ -15,7 +15,12 @@ done
 
 shift $(($OPTIND - 1))
 
-version=$1
+if [ -t 0 ]
+then
+    version=$1
+else
+    version=$(cat)
+fi
 
 # Build array from version string.