diff --git a/CHANGELOG b/CHANGELOG
index 0f7e0ad..b5e231b 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+0.5.1
+-----
+
+* Fix accidental merge with SNAPSHOT version in to master
+
 0.5.0
 -----
 
@@ -9,7 +14,6 @@ CHANGELOG
 * Add `BeanBuilder` experiment
 * Upgrade `lombok` to 1.16.20
 * Upgrade assertj to 3.9.1
-* jenkins: test on both java 8 and 9
 
 0.4.0
 -----
diff --git a/Jenkinsfile.groovy b/Jenkinsfile.groovy
index 7bb06b5..0ef8595 100644
--- a/Jenkinsfile.groovy
+++ b/Jenkinsfile.groovy
@@ -9,12 +9,24 @@ pipeline {
                 git url: gitRepoUrl, branch: '**', credentialsId: 'github-kemitix'
             }
         }
+        stage('no SNAPSHOT in master') {
+            // checks that the pom version is not a snapshot when the current branch is master
+            // TODO: also check for SNAPSHOT when is a pull request with master as the target branch
+            when {
+                expression {
+                    (env.GIT_BRANCH == 'master') &&
+                            (readMavenPom(file: 'pom.xml').version).contains("SNAPSHOT") }
+            }
+            steps {
+                error("Build failed because SNAPSHOT version")
+            }
+        }
         stage('Build') {
             parallel {
                 stage('Java 8') {
                     steps {
                         withMaven(maven: 'maven 3.5.2', jdk: 'JDK 1.8') {
-                            sh 'mvn clean install'
+                            sh "${mvn} clean install"
                         }
                     }
                 }
diff --git a/pom.xml b/pom.xml
index e1b3a89..2c2e95f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -12,7 +12,7 @@
     </parent>
     <groupId>net.kemitix</groupId>
     <artifactId>mon</artifactId>
-    <version>0.5.0-SNAPSHOT</version>
+    <version>0.6.0-SNAPSHOT</version>
 
     <properties>
         <java.version>1.8</java.version>