diff --git a/stats.cpp b/stats.cpp
index b4673dd..2ce9e44 100644
--- a/stats.cpp
+++ b/stats.cpp
@@ -26,8 +26,8 @@ extern int device_map[8];
  */
 void stats_remember_speed(int thr_id, uint32_t hashcount, double hashrate, uint8_t found, uint32_t height)
 {
-	uint64_t gpu = device_map[thr_id];
-	uint64_t key = (gpu << 56) + (uid++ % UINT32_MAX);
+	const uint8_t  gpu = (uint8_t) device_map[thr_id];
+	const uint64_t key = ((uid++ % UINT32_MAX) << 32) + gpu;
 	stats_data data;
 	// to enough hashes to give right stats
 	if (hashcount < 1000 || hashrate < 0.01)
@@ -38,7 +38,7 @@ void stats_remember_speed(int thr_id, uint32_t hashcount, double hashrate, uint8
 		return;
 
 	memset(&data, 0, sizeof(data));
-	data.gpu_id = (uint8_t)gpu;
+	data.gpu_id = gpu;
 	data.thr_id = (uint8_t)thr_id;
 	data.tm_stat = (uint32_t) time(NULL);
 	data.height = height;
@@ -61,16 +61,15 @@ void stats_remember_speed(int thr_id, uint32_t hashcount, double hashrate, uint8
  */
 double stats_get_speed(int thr_id, double def_speed)
 {
-	uint64_t gpu = device_map[thr_id];
-	uint64_t keypfx = (gpu << 56);
-	uint64_t keymsk = (0xffULL << 56);
+	const uint64_t gpu = device_map[thr_id];
+	const uint64_t keymsk = 0xffULL; // last u8 is the gpu
 	double speed = 0.0;
 	int records = 0;
 
 	std::map<uint64_t, stats_data>::reverse_iterator i = tlastscans.rbegin();
 	while (i != tlastscans.rend() && records < opt_statsavg) {
 		if (!i->second.ignored)
-		if (thr_id == -1 || (keymsk & i->first) == keypfx) {
+		if (thr_id == -1 || (keymsk & i->first) == gpu) {
 			if (i->second.hashcount > 1000) {
 				speed += i->second.hashrate;
 				records++;
@@ -93,16 +92,15 @@ double stats_get_speed(int thr_id, double def_speed)
 
 int stats_get_history(int thr_id, struct stats_data *data, int max_records)
 {
-	uint64_t gpu = device_map[thr_id];
-	uint64_t keypfx = (gpu << 56);
-	uint64_t keymsk = (0xffULL << 56);
+	const uint64_t gpu = device_map[thr_id];
+	const uint64_t keymsk = 0xffULL; // last u8 is the gpu
 	double speed = 0.0;
 	int records = 0;
 
 	std::map<uint64_t, stats_data>::reverse_iterator i = tlastscans.rbegin();
 	while (i != tlastscans.rend() && records < max_records) {
 		if (!i->second.ignored)
-			if (thr_id == -1 || (keymsk & i->first) == keypfx) {
+			if (thr_id == -1 || (keymsk & i->first) == gpu) {
 				memcpy(&data[records], &(i->second), sizeof(struct stats_data));
 				records++;
 			}