diff --git a/util.cpp b/util.cpp
index fee037a..c6555dc 100644
--- a/util.cpp
+++ b/util.cpp
@@ -906,11 +906,53 @@ static const char *get_stratum_session_id(json_t *val)
 	return NULL;
 }
 
+static bool stratum_parse_extranonce(struct stratum_ctx *sctx, json_t *params, int pndx)
+{
+	const char* xnonce1;
+	int xn2_size;
+
+	xnonce1 = json_string_value(json_array_get(params, pndx));
+	if (!xnonce1) {
+		applog(LOG_ERR, "Failed to get extranonce1");
+		goto out;
+	}
+	xn2_size = json_integer_value(json_array_get(params, pndx+1));
+	if (!xn2_size) {
+		applog(LOG_ERR, "Failed to get extranonce2_size");
+		goto out;
+	}
+	if (xn2_size < 2 || xn2_size > 16) {
+		applog(LOG_INFO, "Failed to get valid n2size in parse_extranonce");
+		goto out;
+	}
+
+	pthread_mutex_lock(&sctx->work_lock);
+	if (sctx->xnonce1)
+		free(sctx->xnonce1);
+	sctx->xnonce1_size = strlen(xnonce1) / 2;
+	sctx->xnonce1 = (uchar*) calloc(1, sctx->xnonce1_size);
+	if (unlikely(!sctx->xnonce1)) {
+		applog(LOG_ERR, "Failed to alloc xnonce1");
+		pthread_mutex_unlock(&sctx->work_lock);
+		goto out;
+	}
+	hex2bin(sctx->xnonce1, xnonce1, sctx->xnonce1_size);
+	sctx->xnonce2_size = xn2_size;
+	pthread_mutex_unlock(&sctx->work_lock);
+
+	if (pndx == 0 && opt_debug) /* pool dynamic change */
+		applog(LOG_DEBUG, "Stratum set nonce %s with extranonce2 size=%d",
+			xnonce1, xn2_size);
+
+	return true;
+out:
+	return false;
+}
+
 bool stratum_subscribe(struct stratum_ctx *sctx)
 {
 	char *s, *sret = NULL;
-	const char *sid, *xnonce1;
-	int xn2_size;
+	const char *sid;
 	json_t *val = NULL, *res_val, *err_val;
 	json_error_t err;
 	bool ret = false, retry = false;
@@ -927,7 +969,7 @@ start:
 	if (!stratum_send_line(sctx, s))
 		goto out;
 
-	if (!socket_full(sctx->sock, 30)) {
+	if (!socket_full(sctx->sock, 10)) {
 		applog(LOG_ERR, "stratum_subscribe timed out");
 		goto out;
 	}
@@ -959,33 +1001,20 @@ start:
 		goto out;
 	}
 
+	// session id
 	sid = get_stratum_session_id(res_val);
-	if (opt_debug && !sid)
-		applog(LOG_DEBUG, "Failed to get Stratum session id");
-	xnonce1 = json_string_value(json_array_get(res_val, 1));
-	if (!xnonce1) {
-		applog(LOG_ERR, "Failed to get extranonce1");
-		goto out;
-	}
-	xn2_size = json_integer_value(json_array_get(res_val, 2));
-	if (!xn2_size) {
-		applog(LOG_ERR, "Failed to get extranonce2_size");
-		goto out;
-	}
+	if (opt_debug && sid)
+		applog(LOG_DEBUG, "Stratum session id: %s", sid);
 
 	pthread_mutex_lock(&sctx->work_lock);
-	free(sctx->session_id);
-	free(sctx->xnonce1);
+	if (sctx->session_id)
+		free(sctx->session_id);
 	sctx->session_id = sid ? strdup(sid) : NULL;
-	sctx->xnonce1_size = strlen(xnonce1) / 2;
-	sctx->xnonce1 = (uchar*) malloc(sctx->xnonce1_size);
-	hex2bin(sctx->xnonce1, xnonce1, sctx->xnonce1_size);
-	sctx->xnonce2_size = xn2_size;
 	sctx->next_diff = 1.0;
 	pthread_mutex_unlock(&sctx->work_lock);
 
-	if (opt_debug && sid)
-		applog(LOG_DEBUG, "Stratum session id: %s", sctx->session_id);
+	// sid is param 1, extranonce params are 2 and 3
+	stratum_parse_extranonce(sctx, res_val, 1);
 
 	ret = true;
 
@@ -1034,6 +1063,9 @@ bool stratum_authorize(struct stratum_ctx *sctx, const char *user, const char *p
 		goto out;
 	}
 
+	if (json_integer_value(json_object_get(val, "id")) != 2) {
+		applog(LOG_WARNING, "Stratum answer id is not correct!");
+	}
 	res_val = json_object_get(val, "result");
 	err_val = json_object_get(val, "error");
 
@@ -1045,6 +1077,34 @@ bool stratum_authorize(struct stratum_ctx *sctx, const char *user, const char *p
 
 	ret = true;
 
+	// subscribe to extranonce (optional)
+	sprintf(s, "{\"id\": 3, \"method\": \"mining.extranonce.subscribe\", \"params\": []}");
+
+	if (!stratum_send_line(sctx, s))
+		goto out;
+
+	if (!socket_full(sctx->sock, 3)) {
+		applog(LOG_ERR, "stratum extranonce subscribe timed out");
+		goto out;
+	}
+
+	sret = stratum_recv_line(sctx);
+	if (sret) {
+		json_t *extra = JSON_LOADS(sret, &err);
+		free(sret);
+		if (!extra) {
+			applog(LOG_WARNING, "JSON decode failed(%d): %s", err.line, err.text);
+		} else {
+			if (json_integer_value(json_object_get(extra, "id")) != 3) {
+				applog(LOG_WARNING, "Stratum answer id is not correct!");
+			}
+			res_val = json_object_get(extra, "result");
+			if (opt_debug && (!res_val || json_is_false(res_val)))
+				applog(LOG_DEBUG, "extranonce subscribe not supported");
+			json_decref(extra);
+		}
+	}
+
 out:
 	free(s);
 	if (val)
@@ -1304,6 +1364,10 @@ bool stratum_handle_method(struct stratum_ctx *sctx, const char *s)
 		ret = stratum_set_difficulty(sctx, params);
 		goto out;
 	}
+	if (!strcasecmp(method, "mining.set_extranonce")) {
+		ret = stratum_parse_extranonce(sctx, params, 0);
+		goto out;
+	}
 	if (!strcasecmp(method, "client.reconnect")) {
 		ret = stratum_reconnect(sctx, params);
 		goto out;