diff --git a/miner.h b/miner.h
index fc753c9e..1b735aea 100644
--- a/miner.h
+++ b/miner.h
@@ -966,7 +966,7 @@ extern pthread_rwlock_t netacc_lock;
 
 extern const uint32_t sha256_init_state[];
 #ifdef HAVE_LIBCURL
-extern json_t *json_rpc_call(CURL *curl, const char *url, const char *userpass,
+extern json_t *json_rpc_call(CURL *curl, char *curl_err_str, const char *url, const char *userpass,
 			     const char *rpc_req, bool, bool, int *,
 			     struct pool *pool, bool);
 #endif
@@ -1110,6 +1110,7 @@ typedef struct _dev_blk_ctx {
 
 struct curl_ent {
 	CURL *curl;
+	char curl_err_str[CURL_ERROR_SIZE];
 	struct list_head node;
 	struct timeval tv;
 };
diff --git a/sgminer.c b/sgminer.c
index 72366d08..1e9a5a27 100644
--- a/sgminer.c
+++ b/sgminer.c
@@ -1918,12 +1918,13 @@ static void update_gbt(struct pool *pool)
   int rolltime;
   json_t *val;
   CURL *curl;
+  char curl_err_str[CURL_ERROR_SIZE];
 
   curl = curl_easy_init();
   if (unlikely(!curl))
     quit (1, "CURL initialisation failed in update_gbt");
 
-  val = json_rpc_call(curl, pool->rpc_url, pool->rpc_userpass,
+  val = json_rpc_call(curl, curl_err_str, pool->rpc_url, pool->rpc_userpass,
           pool->rpc_req, true, false, &rolltime, pool, false);
 
   if (val) {
@@ -2172,7 +2173,7 @@ out:
 #else /* HAVE_LIBCURL */
 /* Always true with stratum */
 #define pool_localgen(pool) (true)
-#define json_rpc_call(curl, url, userpass, rpc_req, probe, longpoll, rolltime, pool, share) (NULL)
+#define json_rpc_call(curl, curl_err_str, url, userpass, rpc_req, probe, longpoll, rolltime, pool, share) (NULL)
 #define work_decode(pool, work, val) (false)
 #define gen_gbt_work(pool, work) {}
 #endif /* HAVE_LIBCURL */
@@ -2844,7 +2845,7 @@ static void print_status(int thr_id)
     text_print_status(thr_id);
 }
 
-static bool submit_upstream_work(struct work *work, CURL *curl, bool resubmit)
+static bool submit_upstream_work(struct work *work, CURL *curl, char *curl_err_str, bool resubmit)
 {
   char *hexstr = NULL;
   json_t *val, *res, *err;
@@ -2913,7 +2914,7 @@ static bool submit_upstream_work(struct work *work, CURL *curl, bool resubmit)
 
   cgtime(&tv_submit);
   /* issue JSON-RPC request */
-  val = json_rpc_call(curl, pool->rpc_url, pool->rpc_userpass, s, false, false, &rolltime, pool, true);
+  val = json_rpc_call(curl, curl_err_str, pool->rpc_url, pool->rpc_userpass, s, false, false, &rolltime, pool, true);
   cgtime(&tv_submit_reply);
   free(s);
 
@@ -3015,7 +3016,7 @@ out:
   return rc;
 }
 
-static bool get_upstream_work(struct work *work, CURL *curl)
+static bool get_upstream_work(struct work *work, CURL *curl, char *curl_err_str)
 {
   struct pool *pool = work->pool;
   struct sgminer_pool_stats *pool_stats = &(pool->sgminer_pool_stats);
@@ -3030,7 +3031,7 @@ static bool get_upstream_work(struct work *work, CURL *curl)
 
   cgtime(&work->tv_getwork);
 
-  val = json_rpc_call(curl, url, pool->rpc_userpass, pool->rpc_req, false,
+  val = json_rpc_call(curl, curl_err_str, url, pool->rpc_userpass, pool->rpc_req, false,
           false, &work->rolltime, pool, false);
   pool_stats->getwork_attempts++;
 
@@ -3571,7 +3572,7 @@ static void *submit_work_thread(void *userdata)
 
   ce = pop_curl_entry(pool);
   /* submit solution to bitcoin via JSON-RPC */
-  while (!submit_upstream_work(work, ce->curl, resubmit)) {
+  while (!submit_upstream_work(work, ce->curl, ce->curl_err_str, resubmit)) {
     if (opt_lowmem) {
       applog(LOG_NOTICE, "%s share being discarded to minimise memory cache", get_pool_name(pool));
       break;
@@ -5779,6 +5780,7 @@ static bool pool_active(struct pool *pool, bool pinging)
   bool ret = false;
   json_t *val;
   CURL *curl;
+  char curl_err_str[CURL_ERROR_SIZE];
   int rolltime = 0;
 
   if (pool->has_gbt)
@@ -5816,7 +5818,7 @@ retry_stratum:
   /* Probe for GBT support on first pass */
   if (!pool->probed) {
     applog(LOG_DEBUG, "Probing for GBT support");
-    val = json_rpc_call(curl, pool->rpc_url, pool->rpc_userpass,
+    val = json_rpc_call(curl, curl_err_str, pool->rpc_url, pool->rpc_userpass,
             gbt_req, true, false, &rolltime, pool, false);
     if (val) {
       bool append = false, submit = false;
@@ -5861,7 +5863,7 @@ retry_stratum:
   }
 
   cgtime(&tv_getwork);
-  val = json_rpc_call(curl, pool->rpc_url, pool->rpc_userpass,
+  val = json_rpc_call(curl, curl_err_str, pool->rpc_url, pool->rpc_userpass,
           pool->rpc_req, true, false, &rolltime, pool, false);
   cgtime(&tv_getwork_reply);
 
@@ -5927,7 +5929,7 @@ retry_stratum:
         pool->lp_url = (char *)malloc(siz);
         if (!pool->lp_url) {
           applog(LOG_ERR, "Malloc failure in pool_active");
-          return false;
+          goto out;
         }
 
         snprintf(pool->lp_url, siz, "%s%s%s", pool->rpc_url, need_slash ? "/" : "", copy_start);
@@ -6753,6 +6755,7 @@ static void *longpoll_thread(void *userdata)
   struct pool *pool = NULL;
   char threadname[16];
   CURL *curl = NULL;
+  char curl_err_str[CURL_ERROR_SIZE];
   int failures = 0;
   char lpreq[1024];
   char *lp_url;
@@ -6824,7 +6827,7 @@ retry_pool:
      * so always establish a fresh connection instead of relying on
      * a persistent one. */
     curl_easy_setopt(curl, CURLOPT_FRESH_CONNECT, 1);
-    val = json_rpc_call(curl, lp_url, pool->rpc_userpass,
+    val = json_rpc_call(curl, curl_err_str, lp_url, pool->rpc_userpass,
             lpreq, false, true, &rolltime, pool, false);
 
     cgtime(&reply);
@@ -8326,7 +8329,7 @@ retry:
     work->pool = pool;
     ce = pop_curl_entry(pool);
     /* obtain new work from bitcoin via JSON-RPC */
-    if (!get_upstream_work(work, ce->curl)) {
+    if (!get_upstream_work(work, ce->curl, ce->curl_err_str)) {
       applog(LOG_DEBUG, "%s json_rpc_call failed on get work, retrying in 5s", get_pool_name(pool));
       /* Make sure the pool just hasn't stopped serving
        * requests but is up as we'll keep hammering it */
diff --git a/util.c b/util.c
index 34c4792e..b0def66c 100644
--- a/util.c
+++ b/util.c
@@ -113,12 +113,10 @@ struct header_info {
 
 static void databuf_free(struct data_buffer *db)
 {
-	if (!db)
-		return;
-
-	free(db->buf);
-
-	memset(db, 0, sizeof(*db));
+	if (db) {
+		if (db->buf) free(db->buf);
+		memset(db, 0, sizeof(*db));
+	}
 }
 
 static size_t all_data_cb(const void *ptr, size_t size, size_t nmemb,
@@ -130,17 +128,19 @@ static size_t all_data_cb(const void *ptr, size_t size, size_t nmemb,
 	void *newmem;
 	static const unsigned char zero = 0;
 
-	oldlen = db->len;
-	newlen = oldlen + len;
+	if (len > 0) {
+		oldlen = db->len;
+		newlen = oldlen + len;
 
-	newmem = realloc(db->buf, newlen + 1);
-	if (!newmem)
-		return 0;
+		newmem = realloc(db->buf, newlen + 1);
+		if (!newmem)
+			return 0;
 
-	db->buf = newmem;
-	db->len = newlen;
-	memcpy((uint8_t*)db->buf + oldlen, ptr, len);
-	memcpy((uint8_t*)db->buf + newlen, &zero, 1);	/* null terminate */
+		db->buf = newmem;
+		db->len = newlen;
+		memcpy((uint8_t*)db->buf + oldlen, ptr, len);
+		memcpy((uint8_t*)db->buf + newlen, &zero, 1);	/* null terminate */
+	}
 
 	return len;
 }
@@ -154,7 +154,7 @@ static size_t upload_data_cb(void *ptr, size_t size, size_t nmemb,
 	if (len > ub->len)
 		len = ub->len;
 
-	if (len) {
+	if (len > 0) {
 		memcpy(ptr, ub->buf, len);
 		ub->buf = (uint8_t*)ub->buf + len;
 		ub->len -= len;
@@ -298,7 +298,7 @@ static int curl_debug_cb(__maybe_unused CURL *handle, curl_infotype type,
 	return 0;
 }
 
-json_t *json_rpc_call(CURL *curl, const char *url,
+json_t *json_rpc_call(CURL *curl, char *curl_err_str, const char *url,
 		      const char *userpass, const char *rpc_req,
 		      bool probe, bool longpoll, int *rolltime,
 		      struct pool *pool, bool share)
@@ -307,7 +307,6 @@ json_t *json_rpc_call(CURL *curl, const char *url,
 	struct data_buffer all_data = {NULL, 0};
 	struct header_info hi = {NULL, 0, NULL, NULL, false, false, false};
 	char len_hdr[64], user_agent_hdr[128];
-	char curl_err_str[CURL_ERROR_SIZE];
 	struct curl_slist *headers = NULL;
 	struct upload_buffer upload_data;
 	json_t *val, *err_val, *res_val;
@@ -1221,7 +1220,7 @@ bool extract_sockaddr(char *url, char **sockaddr_url, char **sockaddr_port)
 
 	if (url_len < 1)
 		return false;
-	
+
 	if (url_len >= sizeof(url_address))
 	{
 		applog(LOG_WARNING, "%s: Truncating overflowed address '%.*s'",