diff --git a/__tests__/authutil.test.ts b/__tests__/authutil.test.ts
index ec0617cc..9b02367c 100644
--- a/__tests__/authutil.test.ts
+++ b/__tests__/authutil.test.ts
@@ -173,7 +173,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}registry=https://registry.npmjs.org/`
+      `//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 
@@ -182,7 +182,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `@myscope:registry=MMM${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}registry=https://registry.npmjs.org/`
+      `@myscope:registry=MMM${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 
@@ -191,7 +191,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `@myscope:registry=NNN${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}registry=https://registry.npmjs.org/`
+      `@myscope:registry=NNN${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 
@@ -201,7 +201,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/`
+      `//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 
@@ -211,7 +211,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `registry=NNN${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/`
+      `registry=NNN${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 
@@ -221,7 +221,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `registry=MMM${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/`
+      `registry=MMM${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 
@@ -234,7 +234,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `@otherscope:registry=NNN${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/`
+      `@otherscope:registry=NNN${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 
@@ -244,7 +244,7 @@ describe('authutil tests', () => {
     await auth.configAuthentication('https://registry.npmjs.org/');
     const contents = fs.readFileSync(rcFile, {encoding: 'utf8'});
     expect(contents).toBe(
-      `@otherscope:registry=MMM${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/`
+      `@otherscope:registry=MMM${os.EOL}//registry.npmjs.org/:_authToken=\${NODE_AUTH_TOKEN}${os.EOL}@myscope:registry=https://registry.npmjs.org/${os.EOL}`
     );
   });
 });
diff --git a/src/authutil.ts b/src/authutil.ts
index 37d8cfe1..8f0e2b0e 100644
--- a/src/authutil.ts
+++ b/src/authutil.ts
@@ -44,6 +44,9 @@ function writeRegistryToFile(registryUrl: string, fileLocation: string) {
     registryUrl.replace(/(^\w+:|^)/, '') + ':_authToken=${NODE_AUTH_TOKEN}';
   const registryString = `${scope}registry=${registryUrl}`;
   newContents += `${authString}${os.EOL}${registryString}`;
+  if (newContents && !newContents.endsWith(os.EOL)) {
+    newContents += os.EOL;
+  }
   fs.writeFileSync(fileLocation, newContents);
   core.exportVariable('NPM_CONFIG_USERCONFIG', fileLocation);
   // Only export NODE_AUTH_TOKEN if explicitly provided by user