diff --git a/version-bump.mjs b/version-bump.mjs
index fd3925d..cb5226f 100644
--- a/version-bump.mjs
+++ b/version-bump.mjs
@@ -11,7 +11,7 @@ writeFileSync("manifest.json", JSON.stringify(manifest, null, "\t"));
 // update versions.json with target version and minAppVersion from manifest.json
 // but only if the target version is not already in versions.json
 const versions = JSON.parse(readFileSync('versions.json', 'utf8'));
-if (!versions[targetVersion]) {
-    versions[targetVersion] = minAppVersion;
-    writeFileSync('versions.json', JSON.stringify(versions, null, '\t'));
+if (!(targetVersion in versions)) {
+	versions[targetVersion] = minAppVersion;
+	writeFileSync('versions.json', JSON.stringify(versions, null, '\t'));
 }