diff --git a/CHANGELOG.md b/CHANGELOG.md
index 63090a267..53e24f855 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,11 @@
  - Added `--api-no-ipv6` and similar config option to disable IPv6 support for HTTP API.
  - Added `--api-no-restricted` to enable full access to api, this option has no effect if `--api-access-token` not specified.
 
+# v2.5.3
+- Fixed critical bug, in some cases miner was can't recovery connection and switch to failover pool, version 2.5.2 affected. If you use v2.6.0-beta3 this issue doesn't concern you.
+- [#499](https://github.com/xmrig/xmrig/issues/499) IPv6 support disabled for internal HTTP API.
+- Added workaround for nicehash.com if you use `cryptonightv7.<region>.nicehash.com` option `variant=1` will be set automatically.
+
 # v2.5.2
 - [#448](https://github.com/xmrig/xmrig/issues/478) Fixed broken reconnect.
 
diff --git a/src/workers/Hashrate.cpp b/src/workers/Hashrate.cpp
index 60d3a6a29..42068eb72 100644
--- a/src/workers/Hashrate.cpp
+++ b/src/workers/Hashrate.cpp
@@ -151,10 +151,10 @@ void Hashrate::add(size_t threadId, uint64_t count, uint64_t timestamp)
 
 void Hashrate::print()
 {
-    char num1[8];
-    char num2[8];
-    char num3[8];
-    char num4[8];
+    char num1[8] = { 0 };
+    char num2[8] = { 0 };
+    char num3[8] = { 0 };
+    char num4[8] = { 0 };
 
     LOG_INFO(m_controller->config()->isColors() ? "\x1B[01;37mspeed\x1B[0m 2.5s/60s/15m \x1B[01;36m%s \x1B[22;36m%s %s \x1B[01;36mH/s\x1B[0m max: \x1B[01;36m%s H/s" : "speed 2.5s/60s/15m %s %s %s H/s max: %s H/s",
              format(calc(ShortInterval),  num1, sizeof(num1)),