diff --git a/dev-packages/size-limit-gh-action/index.mjs b/dev-packages/size-limit-gh-action/index.mjs
index 43f4f3a96f65..7ff44e0dd8a6 100644
--- a/dev-packages/size-limit-gh-action/index.mjs
+++ b/dev-packages/size-limit-gh-action/index.mjs
@@ -187,7 +187,7 @@ async function run() {
     const githubToken = getInput('github_token');
     const threshold = getInput('threshold');
 
-    if (!comparisonBranch && !pr) {
+    if (comparisonBranch && !pr) {
       throw new Error('No PR found. Only pull_request workflows are supported.');
     }