diff --git a/src/index.ts b/src/index.ts
index d8d1cc9d..d6060658 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -77,8 +77,8 @@ const getOptionalInput = (name: string) => core.getInput(name) || undefined;
           core.info("Found existing user .npmrc file");
           const userNpmrcContent = await fs.readFile(userNpmrcPath, "utf8");
           const authLine = userNpmrcContent.split("\n").find((line) => {
-            // check based on https://github.com/npm/cli/blob/8f8f71e4dd5ee66b3b17888faad5a7bf6c657eed/test/lib/adduser.js#L103-L105
-            return /^\s*\/\/registry\.npmjs\.org\/:[_-]authToken=/i.test(line);
+            // URL-shaped registry key + :_authToken=… (http(s):// or //)
+            return /^\s*(?:https?:\/\/|\/\/).+:[_-]authToken=/i.test(line);
           });
           if (authLine) {
             core.info(