diff --git a/cpu/esp32/README.md b/cpu/esp32/README.md
index 519bcb8386..31ae327408 100644
--- a/cpu/esp32/README.md
+++ b/cpu/esp32/README.md
@@ -330,9 +330,9 @@ git checkout -q 534a9b14101af90231d40a4f94924d67bc848d5f
 
 **Please note:** Please take care to checkout correct branches which were used for the port. Newer versions might also work but were not tested.
 
-Since we only use a few header files, ESP-IDF does not need to be compiled in any way. To use the installed ESP-IDF, just set the variable ```SDK_DIR``` accordingly.
+Since we only use a few header files, ESP-IDF does not need to be compiled in any way. To use the installed ESP-IDF, just set the variable ```ESP32_SDK_DIR``` accordingly.
 ```
-export SDK_DIR=$HOME/esp/esp-idf
+export ESP32_SDK_DIR=$HOME/esp/esp-idf
 ```
 
 
@@ -350,7 +350,7 @@ Once you have installed all required components, you should have the following d
 To use the toolchain and optionally the SDK, please check that your environment variables are set correctly to
 
 ```
-export SDK_DIR=/path/to/esp/esp-idf
+export ESP32_SDK_DIR=/path/to/esp/esp-idf
 export PATH=$PATH:/path/to/esp/xtensa-esp32-elf/bin
 ```
 
diff --git a/cpu/esp32/doc.txt b/cpu/esp32/doc.txt
index 3893c54a4d..ad33873f5d 100644
--- a/cpu/esp32/doc.txt
+++ b/cpu/esp32/doc.txt
@@ -344,9 +344,9 @@ git checkout -q 534a9b14101af90231d40a4f94924d67bc848d5f
 
 @note Please take care to checkout correct branches which were used for the port. Newer versions might also work but were not tested.
 
-Since we only use a few header files, ESP-IDF does not need to be compiled in any way. To use the installed ESP-IDF, just set the variable ```SDK_DIR``` accordingly.
+Since we only use a few header files, ESP-IDF does not need to be compiled in any way. To use the installed ESP-IDF, just set the variable ```ESP32_SDK_DIR``` accordingly.
 ```
-export SDK_DIR=$HOME/esp/esp-idf
+export ESP32_SDK_DIR=$HOME/esp/esp-idf
 ```
 
 
@@ -364,7 +364,7 @@ Once you have installed all required components, you should have the following d
 To use the toolchain and optionally the SDK, please check that your environment variables are set correctly to
 
 ```
-export SDK_DIR=/path/to/esp/esp-idf
+export ESP32_SDK_DIR=/path/to/esp/esp-idf
 export PATH=$PATH:/path/to/esp/xtensa-esp32-elf/bin
 ```