diff --git a/HISTORY.rst b/HISTORY.rst
index 9adb24f5..8b0336e6 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -7,6 +7,8 @@ PlatformIO 3.0
 3.5.4 (2018-??-??)
 ~~~~~~~~~~~~~~~~~~
 
+* Improved removing of default build flags using `build_unflags <http://docs.platformio.org/page/projectconf/section_env_build.html#build-unflags>`__ option
+  (`issue #1712 <https://github.com/platformio/platformio-core/issues/1712>`_)
 * Export ``LIBS``, ``LIBPATH``, and ``LINKFLAGS`` data from project dependent
   libraries to the global build environment
 * Don't export ``CPPPATH`` data of project dependent libraries to framework's
diff --git a/platformio/builder/tools/platformio.py b/platformio/builder/tools/platformio.py
index ac3dda2b..0d82bbed 100644
--- a/platformio/builder/tools/platformio.py
+++ b/platformio/builder/tools/platformio.py
@@ -190,7 +190,18 @@ def ProcessFlags(env, flags):  # pylint: disable=too-many-branches
 def ProcessUnFlags(env, flags):
     if not flags:
         return
-    for key, unflags in env.ParseFlagsExtended(flags).items():
+    parsed = env.ParseFlagsExtended(flags)
+
+    # get all flags and copy them to each "*FLAGS" variable
+    all_flags = []
+    for key, unflags in parsed.items():
+        if key.endswith("FLAGS"):
+            all_flags.extend(unflags)
+    for key, unflags in parsed.items():
+        if key.endswith("FLAGS"):
+            parsed[key].extend(all_flags)
+
+    for key, unflags in parsed.items():
         for unflag in unflags:
             for current in env.get(key, []):
                 conditions = [