diff --git a/dist/index.js b/dist/index.js
index 5e4739a..798e67e 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -4847,6 +4847,9 @@ function configAuthentication(feedUrl, existingFileLocation = '', processRoot =
     writeFeedToFile(feedUrl, existingNuGetConfig, tempNuGetConfig);
 }
 exports.configAuthentication = configAuthentication;
+function isValidKey(key) {
+    return /^[\w\-\.]+$/i.test(key);
+}
 function getExistingNugetConfig(processRoot) {
     const defaultConfigName = 'nuget.config';
     const configFileNames = fs
@@ -4922,8 +4925,8 @@ function writeFeedToFile(feedUrl, existingFileLocation, tempFileLocation) {
     }
     xml = xml.ele('packageSourceCredentials');
     sourceKeys.forEach(key => {
-        if (key.indexOf(' ') > -1) {
-            throw new Error("This action currently can't handle source names with spaces. Remove the space from your repo's NuGet.config and try again.");
+        if (!isValidKey(key)) {
+            throw new Error("Source name can contain letters, numbers, and '-', '_', '.' symbols only. Please, fix source name in NuGet.config and try again.");
         }
         xml = xml
             .ele(key)
diff --git a/src/authutil.ts b/src/authutil.ts
index d8ddef0..9599979 100644
--- a/src/authutil.ts
+++ b/src/authutil.ts
@@ -27,6 +27,10 @@ export function configAuthentication(
   writeFeedToFile(feedUrl, existingNuGetConfig, tempNuGetConfig);
 }
 
+function isValidKey(key: string): boolean {
+  return /^[\w\-\.]+$/i.test(key);
+}
+
 function getExistingNugetConfig(processRoot: string) {
   const defaultConfigName = 'nuget.config';
   const configFileNames = fs
@@ -122,9 +126,9 @@ function writeFeedToFile(
   xml = xml.ele('packageSourceCredentials');
 
   sourceKeys.forEach(key => {
-    if (key.indexOf(' ') > -1) {
+    if (!isValidKey(key)) {
       throw new Error(
-        "This action currently can't handle source names with spaces. Remove the space from your repo's NuGet.config and try again."
+        "Source name can contain letters, numbers, and '-', '_', '.' symbols only. Please, fix source name in NuGet.config and try again."
       );
     }