diff --git a/HISTORY.rst b/HISTORY.rst
index 0c25869e..ceef275e 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -11,6 +11,7 @@ PlatformIO Core 4.0
 
 * Handle project configuration (monitor, test, and upload options) for PIO Remote commands (`issue #2591 <https://github.com/platformio/platformio-core/issues/2591>`_)
 * Fixed an issue with the broken latest news for PIO Home
+* Fixed an issue when ``env.BoardConfig()`` does not work for custom boards in extra scripts of libraries (`issue #3264 <https://github.com/platformio/platformio-core/issues/3264>`_)
 
 4.1.0 (2019-11-07)
 ~~~~~~~~~~~~~~~~~~
diff --git a/platformio/builder/tools/pioplatform.py b/platformio/builder/tools/pioplatform.py
index f910aaed..a7fbb8b9 100644
--- a/platformio/builder/tools/pioplatform.py
+++ b/platformio/builder/tools/pioplatform.py
@@ -44,7 +44,8 @@ def BoardConfig(env, board=None):
     try:
         board = board or env.get("BOARD")
         assert board, "BoardConfig: Board is not defined"
-        config = p.board_config(board)
+        with fs.cd(env.subst("$PROJECT_DIR")):
+            config = p.board_config(board)
     except (AssertionError, exception.UnknownBoard) as e:
         sys.stderr.write("Error: %s\n" % str(e))
         env.Exit(1)