From 7422b99b42ae0798774ea1d96238b73951222c00 Mon Sep 17 00:00:00 2001
From: Ivan Kravets <me@ikravets.com>
Date: Tue, 14 Jun 2016 20:53:30 +0300
Subject: [PATCH] Process "$BUILD_UNFLAGS" variable

---
 platformio/builder/scripts/frameworks/mbed.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/platformio/builder/scripts/frameworks/mbed.py b/platformio/builder/scripts/frameworks/mbed.py
index 7c04af31..4f8fd57e 100644
--- a/platformio/builder/scripts/frameworks/mbed.py
+++ b/platformio/builder/scripts/frameworks/mbed.py
@@ -266,9 +266,12 @@ env.Replace(
 
 # restore external build flags
 env.ProcessFlags([
-    env.get("BOARD_OPTIONS", {}).get("build", {}).get("extra_flags"),
-    env.get("BUILD_FLAGS")
+    env.get("BOARD_OPTIONS", {}).get("build", {}).get("extra_flags")
 ])
+# remove base flags
+env.ProcessUnFlags(env.get("BUILD_UNFLAGS"))
+# apply user flags
+env.ProcessFlags([env.get("BUILD_FLAGS")])
 
 # Hook for K64F and K22F
 if board_type in ("frdm_k22f", "frdm_k64f"):