diff --git a/Compatibility-issues.md b/Compatibility-issues.md
index 71d6190..f697631 100644
--- a/Compatibility-issues.md
+++ b/Compatibility-issues.md
@@ -26,7 +26,7 @@ As I'm writing theses lines, **you need to use the "staging" version because the
 
 See issues [#101](https://github.com/bblanchon/ArduinoJson/issues/101), [#125](https://github.com/bblanchon/ArduinoJson/issues/125), [#155](https://github.com/bblanchon/ArduinoJson/issues/155) and [#185](https://github.com/bblanchon/ArduinoJson/issues/185).
 
-## Intel Edison
+## Intel Edison: compilation error
 
 This is a known bug in [Arduino core for Intel Edison](https://github.com/01org/corelibs-edison).
 A [pull request](https://github.com/01org/corelibs-edison/pull/18) has been submitted but is still waiting for approval.
@@ -38,11 +38,28 @@ Until this gets fixed, just insert the following line in your local `cores/ardui
 On Windows, the file is likely to be located here:
 
 ```
-%APPDATA%\Arduino15\packages\Intel\hardware\i686\1.6.2+1.0\cores\arduino\WString.h
+%LOCALAPPDATA%\Arduino15\packages\Intel\hardware\i686\1.6.2+1.0\cores\arduino\WString.h
 ```
 
 See issues [#123](https://github.com/bblanchon/ArduinoJson/issues/123) and [#138](https://github.com/bblanchon/ArduinoJson/issues/138)
 
+## RedBearLab boards: compilation error
+
+This is a known bug in [Arduino core for BLE Nano](https://github.com/RedBearLab/nRF51822-Arduino).
+A [pull request](https://github.com/RedBearLab/nRF51822-Arduino/pull/57) has been submitted but is still waiting for approval.
+
+Until this gets fixed, just insert the following line in your local `cores/arduino/WString.h`:
+
+    const char * c_str() const { return buffer; }
+
+On Windows, the file is likely to be located here:
+
+```
+%LOCALAPPDATA%\Arduino15\packages\RedBearLab\hardware\nRF51822\1.0.5\cores\RBL_nRF51822\WString.h
+```
+
+See issue [#222](https://github.com/bblanchon/ArduinoJson/issues/222)
+
 ## Teensy, and other Arduino compatible boards
 
 Some platforms need some time to initialize the serial port.