diff --git a/launchers/darwin/src/CredentialsRequest.m b/launchers/darwin/src/CredentialsRequest.m
index d2e7e51573..fd651bd98a 100644
--- a/launchers/darwin/src/CredentialsRequest.m
+++ b/launchers/darwin/src/CredentialsRequest.m
@@ -7,7 +7,9 @@
 - (void) confirmCredentials:(NSString*)username :(NSString*)password {
 
     NSLog(@"web request started");
-    NSString *post = [NSString stringWithFormat:@"grant_type=password&username=%@&password=%@&scope=owner", username, [password stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet symbolCharacterSet]]];
+    NSString *post = [NSString stringWithFormat:@"grant_type=password&username=%@&password=%@&scope=owner",
+        [username stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet alphanumericCharacterSet]],
+        [password stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet alphanumericCharacterSet]]];
     NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding];
     NSString *postLength = [NSString stringWithFormat:@"%ld", (unsigned long)[postData length]];