diff --git a/.rultor.yml b/.rultor.yml
index d313a44..c9196e3 100644
--- a/.rultor.yml
+++ b/.rultor.yml
@@ -16,6 +16,7 @@ merge:
     mvn clean site -Psite --errors --settings ../settings.xml -Dinvoker.skip
 release:
   script: |-
+    [[ "${tag}" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]] || exit -1
     mvn versions:set "-DnewVersion=${tag}"
     git commit -am "${tag}"
     mvn clean deploy -Pxembly -Psonatype --errors --settings ../settings.xml