diff --git a/Source/GTMOAuth2Authentication.m b/Source/GTMOAuth2Authentication.m
index ac1e081..04ec229 100644
--- a/Source/GTMOAuth2Authentication.m
+++ b/Source/GTMOAuth2Authentication.m
@@ -741,7 +741,7 @@ - (GTMOAuth2Fetcher *)beginTokenFetchWithDelegate:(id)delegate
   NSString *code = self.code;
   NSString *assertion = self.assertion;
   NSString *grantType = nil;
-  
+
   if (refreshToken) {
     // We have a refresh token
     grantType = @"refresh_token";
@@ -869,6 +869,7 @@ - (void)tokenFetcher:(GTMOAuth2Fetcher *)fetcher
 
   NSDictionary *responseHeaders = [fetcher responseHeaders];
   NSString *responseType = [responseHeaders valueForKey:@"Content-Type"];
+  // "text/javascript" supports Dropbox's out-of-spec OAuth 2.
   BOOL isResponseJSON = ([responseType hasPrefix:@"application/json"] ||
                          [responseType hasPrefix:@"text/javascript"]);
   BOOL hasData = ([data length] > 0);