diff --git a/src/network/network_content.cpp b/src/network/network_content.cpp
--- a/src/network/network_content.cpp
+++ b/src/network/network_content.cpp
@@ -586,9 +586,7 @@ void ClientNetworkContentSocketHandler::
 	this->http_response_index = -2;
 
 	if (this->curFile != nullptr) {
-		/* Revert the download progress when we are going for the old system. */
-		long size = ftell(this->curFile);
-		if (size > 0) this->OnDownloadProgress(this->curInfo, (int)-size);
+		this->OnDownloadProgress(this->curInfo, -1);
 
 		fclose(this->curFile);
 		this->curFile = nullptr;
diff --git a/src/network/network_content_gui.cpp b/src/network/network_content_gui.cpp
--- a/src/network/network_content_gui.cpp
+++ b/src/network/network_content_gui.cpp
@@ -100,7 +100,7 @@ static WindowDesc _network_content_downl
 );
 
 BaseNetworkContentDownloadStatusWindow::BaseNetworkContentDownloadStatusWindow(WindowDesc *desc) :
-		Window(desc), cur_id(UINT32_MAX)
+		Window(desc), downloaded_bytes(0), downloaded_files(0), cur_id(UINT32_MAX)
 {
 	_network_content_client.AddCallback(this);
 	_network_content_client.DownloadSelectedContent(this->total_files, this->total_bytes);
@@ -174,7 +174,13 @@ void BaseNetworkContentDownloadStatusWin
 		this->downloaded_files++;
 	}
 
-	this->downloaded_bytes += bytes;
+	/* A negative value means we are resetting; for example, when retrying or using a fallback. */
+	if (bytes < 0) {
+		this->downloaded_bytes = 0;
+	} else {
+		this->downloaded_bytes += bytes;
+	}
+
 	this->SetDirty();
 }