diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index cf32c7d..62a11b9 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -53,5 +53,6 @@ jobs:
         displayName: 'Build "pegjs/dist/*.js" files'
       - script: node tools/publish-dev
         displayName: 'Publish to NPM'
-        env:
+        variables:
           NPM_TOKEN: $(NPM_CI_TOKEN)
+          PR_BRANCH: $[ coalesce(variables['System.PullRequest.SourceBranch'], 'not-found') ]
diff --git a/tools/publish-dev/index.js b/tools/publish-dev/index.js
index 699352b..aef33f9 100644
--- a/tools/publish-dev/index.js
+++ b/tools/publish-dev/index.js
@@ -14,9 +14,17 @@ const npmrc = path.join( pegjs, ".npmrc" );
 // variabes
 
 const APP = require( "./package.json" ).name;
-const { GIT_BRANCH, GIT_COMMIT_SHA, NPM_TOKEN } = process.env;
 const VERSION = require( packagejson ).version;
 
+const {
+
+    GIT_BRANCH,
+    GIT_COMMIT_SHA,
+    NPM_TOKEN,
+    PR_BRANCH,
+
+} = process.env;
+
 // local helpers
 
 function die( err ) {
@@ -39,6 +47,13 @@ function exec( command, print = true ) {
 
 // assertions
 
+if ( PR_BRANCH !== "not-found" ) {
+
+    console.log( "Skipping publish, PR's are not published." );
+    process.exit( 0 );
+
+}
+
 if ( ! GIT_BRANCH ) die( "`process.env.GIT_BRANCH` is required by " + APP );
 if ( ! NPM_TOKEN ) die( "`process.env.NPM_TOKEN` is required by " + APP );