diff --git a/source4/auth/gensec/gensec_tstream.c b/source4/auth/gensec/gensec_tstream.c
index 91915b50348..92f4fa6687c 100644
--- a/source4/auth/gensec/gensec_tstream.c
+++ b/source4/auth/gensec/gensec_tstream.c
@@ -247,9 +247,10 @@ static int tstream_gensec_readv_next_vector(struct tstream_context *unix_stream,
 		vector[0].iov_base = (char *)state->wrapped.hdr;
 		vector[0].iov_len = sizeof(state->wrapped.hdr);
 	} else if (!state->wrapped.asked_for_blob) {
-		state->wrapped.asked_for_blob = true;
 		uint32_t msg_len;
 
+		state->wrapped.asked_for_blob = true;
+
 		msg_len = RIVAL(state->wrapped.hdr, 0);
 
 		if (msg_len > 0x00FFFFFF) {