diff --git a/workspace_tools/build_api.py b/workspace_tools/build_api.py
index 847e9cedc9..ddebb18bac 100644
--- a/workspace_tools/build_api.py
+++ b/workspace_tools/build_api.py
@@ -136,18 +136,20 @@ def build_mbed_libs(target, toolchain_name, options=None, verbose=False):
     
     # mbed
     toolchain.info("\n>>> BUILD LIBRARY %s (%s, %s)" % ('MBED', target.name, toolchain_name))
-    HAL_SRC = join(MBED_TARGETS_PATH, "hal")
-    hal_implementation = toolchain.scan_resources(HAL_SRC)
     
-    mbed_resources = toolchain.scan_resources(MBED_COMMON)
-    mbed_resources.add(hal_implementation)
-    
-    # Headers
+    # Common Headers
     toolchain.copy_files(toolchain.scan_resources(MBED_API).headers, MBED_LIBRARIES)
     toolchain.copy_files(toolchain.scan_resources(MBED_HAL).headers, MBED_LIBRARIES)
-    toolchain.copy_files(hal_implementation.headers, BUILD_TARGET)
     
-    objects = toolchain.compile_sources(mbed_resources, TMP_PATH, [MBED_LIBRARIES, BUILD_TARGET])
+    # Target specific sources
+    HAL_SRC = join(MBED_TARGETS_PATH, "hal")
+    hal_implementation = toolchain.scan_resources(HAL_SRC)
+    toolchain.copy_files(hal_implementation.headers, BUILD_TARGET)
+    objects  = toolchain.compile_sources(hal_implementation, TMP_PATH, [MBED_LIBRARIES, BUILD_TARGET])
+    
+    # Common Sources
+    mbed_resources = toolchain.scan_resources(MBED_COMMON)
+    objects += toolchain.compile_sources(mbed_resources, TMP_PATH, [MBED_LIBRARIES, BUILD_TARGET])
     
     # Keep the stdio retargeting as a standalone object to be sure the
     # C standard library symbols get overridden
diff --git a/workspace_tools/export_test.py b/workspace_tools/export_test.py
index 52036a6d9c..a78ea28720 100644
--- a/workspace_tools/export_test.py
+++ b/workspace_tools/export_test.py
@@ -9,12 +9,16 @@ from workspace_tools.export import export
 
 from shutil import copytree
 
+EXPORT_DIR = join(BUILD_DIR, "export_test")
+USER_WORKSPACE = join(EXPORT_DIR, "user_workspace")
 
-USR_PRJ_NAME = "export_test"
-USER_PRJ = join(BUILD_DIR, USR_PRJ_NAME)
+USR_PRJ_NAME = "usr_prj"
+USER_PRJ = join(USER_WORKSPACE, USR_PRJ_NAME)
 USER_LIB = join(USER_PRJ, "lib")
 USER_SRC = join(USER_PRJ, "src")
-TEMP     = join(USER_PRJ, ".temp")
+
+TEMP = join(USER_WORKSPACE, ".temp")
+
 
 def setup_test_user_prj():
     if exists(USER_PRJ):
@@ -50,7 +54,7 @@ def test_export(toolchain, target, expected_error=None):
     zip_path, report = export(USER_PRJ, USR_PRJ_NAME, toolchain, target, base_dir, temp_dir, False, fake_build_url_resolver)
     
     if report['success']:
-        export_name = join(TEMP, "export_%s_%s.zip" % (toolchain, target))
+        export_name = join(EXPORT_DIR, "export_%s_%s.zip" % (toolchain, target))
         cmd(["mv", zip_path, export_name])
         print "[OK]"
     else:
@@ -66,9 +70,6 @@ def test_export(toolchain, target, expected_error=None):
 
 
 if __name__ == '__main__':
-    # import logging as log
-    # log.getLogger().setLevel(log.DEBUG)
-    
     setup_test_user_prj()
     
     for toolchain, target in [
diff --git a/workspace_tools/toolchains/__init__.py b/workspace_tools/toolchains/__init__.py
index 62d5d2d2e3..f694fc540c 100644
--- a/workspace_tools/toolchains/__init__.py
+++ b/workspace_tools/toolchains/__init__.py
@@ -101,6 +101,20 @@ class Resources:
         return '\n'.join(s)
 
 
+# Support legacy build conventions: the original mbed build system did not have
+# standard labels for the "TARGET_" and "TOOLCHAIN_" specific directories, but
+# had the knowledge of a list of these directories to be ignored.
+LEGACY_IGNORE_DIRS = set([
+    'LPC11U24', 'LPC1768', 'LPC2368', 'LPC4088', 'LPC812', 'KL25Z',
+    'ARM', 'GCC_ARM', 'GCC_CR', 'GCC_CS', 'IAR', 'uARM'
+])
+LEGACY_TOOLCHAIN_NAMES = {
+    'ARM_STD':'ARM', 'ARM_MICRO': 'uARM',
+    'GCC_ARM': 'GCC_ARM', 'GCC_CR': 'GCC_CR', 'GCC_CS': 'GCC_CS',
+    'IAR': 'IAR',
+}
+
+
 class mbedToolchain:
     VERBOSE = True
     
@@ -113,6 +127,9 @@ class mbedToolchain:
     
     def __init__(self, target, options=None, notify=None):
         self.target = target
+        self.name = self.__class__.__name__
+        
+        self.legacy_ignore_dirs = LEGACY_IGNORE_DIRS - set([target.name, LEGACY_TOOLCHAIN_NAMES[self.name]])
         
         if notify is not None:
             self.notify = notify
@@ -127,7 +144,6 @@ class mbedToolchain:
         if self.options:
             self.info("Build Options: %s" % (', '.join(self.options)))
         
-        self.name = self.__class__.__name__
         self.obj_path = join(target.name, self.name)
         
         self.symbols = None
@@ -195,7 +211,7 @@ class mbedToolchain:
         for root, dirs, files in walk(path):
             # Remove ignored directories
             for d in copy(dirs):
-                if ((d.startswith('.') or d in set(['CVS'])) or
+                if ((d.startswith('.') or d in self.legacy_ignore_dirs) or
                     (d.startswith('TARGET_') and d[7:] not in labels['TARGET']) or
                     (d.startswith('TOOLCHAIN_') and d[10:] not in labels['TOOLCHAIN'])):
                     dirs.remove(d)