diff --git a/src/mux_h2.c b/src/mux_h2.c
index 4dada0b0c..3810943c5 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -5360,8 +5360,7 @@ static size_t h2s_bck_make_req_headers(struct h2s *h2s, struct htx *htx)
 
 			if (len + 2 < uri.len && uri.ptr[len + 1] == '/' && uri.ptr[len + 2] == '/') {
 				/* make the uri start at the authority now */
-				scheme.ptr = uri.ptr;
-				scheme.len = len;
+				scheme = ist2(uri.ptr, len);
 				uri.ptr += len + 3;
 				uri.len -= len + 3;