diff --git a/Makefile b/Makefile
index 67594305..b06333e6 100644
--- a/Makefile
+++ b/Makefile
@@ -3,7 +3,7 @@
 .NOTPARALLEL:
 
 # SDK version NodeMCU is locked to
-SDK_VER:=1.5.0
+SDK_VER:=1.5.1
 # Ensure we search "our" SDK before the tool-chain's SDK (if any)
 TOP_DIR:=$(abspath $(dir $(lastword $(MAKEFILE_LIST))))
 SDK_DIR:=$(TOP_DIR)/sdk/esp_iot_sdk_v$(SDK_VER)
@@ -171,9 +171,9 @@ $(BINODIR)/%.bin: $(IMAGEODIR)/%.out
 all:	sdk_extracted .subdirs $(OBJS) $(OLIBS) $(OIMAGES) $(OBINS) $(SPECIAL_MKTARGETS)
 
 .PHONY: sdk_extracted
-sdk_extracted: $(TOP_DIR)/sdk/.extracted
+sdk_extracted: $(TOP_DIR)/sdk/.extracted-$(SDK_VER)
 
-$(TOP_DIR)/sdk/.extracted:
+$(TOP_DIR)/sdk/.extracted-$(SDK_VER):
 	mkdir -p "$(dir $@)"
 	(cd "$(dir $@)" && unzip $(TOP_DIR)/cache/esp_iot_sdk_v$(SDK_VER)*.zip esp_iot_sdk_v$(SDK_VER)/lib/* esp_iot_sdk_v$(SDK_VER)/ld/eagle.rom.addr.v6.ld esp_iot_sdk_v$(SDK_VER)/include/* )
 	rm -f $(SDK_DIR)/lib/liblwip.a
diff --git a/README.md b/README.md
index 42eb41eb..855a7c7b 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,10 @@
-# **NodeMCU 1.5.0** #
+# **NodeMCU 1.5.1** #
 
 [![Join the chat at https://gitter.im/nodemcu/nodemcu-firmware](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/nodemcu/nodemcu-firmware?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Build Status](https://travis-ci.org/nodemcu/nodemcu-firmware.svg)](https://travis-ci.org/nodemcu/nodemcu-firmware)
 
 ###A lua based firmware for wifi-soc esp8266
-  - Build on [ESP8266 NONOS SDK 1.5.0](http://bbs.espressif.com/viewtopic.php?f=46&t=1442)
+  - Build on [ESP8266 NONOS SDK 1.5.1](http://bbs.espressif.com/viewtopic.php?f=46&p=5315)
   - Lua core based on [eLua project](http://www.eluaproject.net/)
   - cjson based on [lua-cjson](https://github.com/mpx/lua-cjson)
   - File system based on [spiffs](https://github.com/pellepl/spiffs)
@@ -298,7 +298,7 @@ Comment-out the #define statement for unused modules. Example:
 Identify your firmware builds by editing `app/include/user_version.h`
 
 ```c
-#define NODE_VERSION    "NodeMCU 1.5.0+myname"
+#define NODE_VERSION    "NodeMCU 1.5.1+myname"
 #ifndef BUILD_DATE
 #define BUILD_DATE        "YYYYMMDD"
 #endif
diff --git a/app/include/user_version.h b/app/include/user_version.h
index 0320c381..32aa362a 100644
--- a/app/include/user_version.h
+++ b/app/include/user_version.h
@@ -6,7 +6,7 @@
 #define NODE_VERSION_REVISION	0U
 #define NODE_VERSION_INTERNAL   0U
 
-#define NODE_VERSION	"NodeMCU 1.5.0"
+#define NODE_VERSION	"NodeMCU 1.5.1"
 #ifndef BUILD_DATE
 #define BUILD_DATE	  "unspecified"
 #endif
diff --git a/cache/esp_iot_sdk_v1.5.0_15_11_27.zip b/cache/esp_iot_sdk_v1.5.0_15_11_27.zip
deleted file mode 100644
index d6347195..00000000
Binary files a/cache/esp_iot_sdk_v1.5.0_15_11_27.zip and /dev/null differ
diff --git a/cache/esp_iot_sdk_v1.5.1_16_01_08.zip b/cache/esp_iot_sdk_v1.5.1_16_01_08.zip
new file mode 100644
index 00000000..0e6e4e32
Binary files /dev/null and b/cache/esp_iot_sdk_v1.5.1_16_01_08.zip differ