diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index dc3ed2f..e5c023b 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -55,4 +55,4 @@ jobs:
         displayName: 'Publish to NPM'
         env:
           NPM_TOKEN: $(NPM_CI_TOKEN)
-          PR_BRANCH: $[ coalesce(variables['System.PullRequest.SourceBranch'], 'not-found') ]
+          BUILD_REASON: $(variables['Build.Reason'])
diff --git a/tools/publish-dev/index.js b/tools/publish-dev/index.js
index 1c93f65..7f8111a 100644
--- a/tools/publish-dev/index.js
+++ b/tools/publish-dev/index.js
@@ -18,9 +18,9 @@ const VERSION = require( packagejson ).version;
 
 const {
 
+    BUILD_REASON,
     GIT_BRANCH,
     NPM_TOKEN,
-    PR_BRANCH,
 
 } = process.env;
 
@@ -54,7 +54,7 @@ function exec( command, print = true ) {
 
 // assertions
 
-if ( PR_BRANCH !== "not-found" ) {
+if ( BUILD_REASON && BUILD_REASON === "PullRequest" ) {
 
     console.log( "Skipping publish, PR's are not published." );
     process.exit( 0 );