diff --git a/Common/Net/HTTPClient.cpp b/Common/Net/HTTPClient.cpp
index 43b30f7602..e8d3b6c7f5 100644
--- a/Common/Net/HTTPClient.cpp
+++ b/Common/Net/HTTPClient.cpp
@@ -604,8 +604,8 @@ std::shared_ptr<Download> Downloader::StartDownloadWithCallback(
 std::shared_ptr<Download> Downloader::AsyncPostWithCallback(
 	const std::string &url,
 	const std::string &postData,
+	const std::string &postMime,
 	std::function<void(Download &)> callback) {
-	std::string postMime = "application/x-www-form-urlencoded";
 	std::shared_ptr<Download> dl(new Download(RequestMethod::POST, url, postData, postMime, Path()));
 	dl->SetCallback(callback);
 	newDownloads_.push_back(dl);
diff --git a/Common/Net/HTTPClient.h b/Common/Net/HTTPClient.h
index f6b832b834..7a0a87f3c0 100644
--- a/Common/Net/HTTPClient.h
+++ b/Common/Net/HTTPClient.h
@@ -202,6 +202,7 @@ public:
 	std::shared_ptr<Download> AsyncPostWithCallback(
 		const std::string &url,
 		const std::string &postData,
+		const std::string &postMime, // Use postMime = "application/x-www-form-urlencoded" for standard form-style posts, such as used by retroachievements.
 		std::function<void(Download &)> callback);
 
 	// Drops finished downloads from the list.