diff --git a/UI/win-update/updater/http.cpp b/UI/win-update/updater/http.cpp
index cbea2b3cd..dff46c168 100644
--- a/UI/win-update/updater/http.cpp
+++ b/UI/win-update/updater/http.cpp
@@ -293,10 +293,10 @@ static bool ReadHTTPZippedFile(z_stream *strm, HANDLE updateFile,
 		string &zipBuf, const uint8_t *buffer, DWORD outSize,
 		int *responseCode)
 {
-	do {
-		strm->avail_in = outSize;
-		strm->next_in  = buffer;
+	strm->avail_in = outSize;
+	strm->next_in  = buffer;
 
+	do {
 		strm->avail_out = (uInt)zipBuf.size();
 		strm->next_out  = (Bytef *)zipBuf.data();