diff --git a/platformio/builder/main.py b/platformio/builder/main.py
index 6930e96c..0a0d13d3 100644
--- a/platformio/builder/main.py
+++ b/platformio/builder/main.py
@@ -48,7 +48,7 @@ commonvars.AddVariables(
 )
 
 DefaultEnvironment(
-    tools=["gcc", "g++", "ar", "gnulink", "platformio"],
+    tools=["gcc", "g++", "as", "ar", "gnulink", "platformio"],
     toolpath=[join("$PIOBUILDER_DIR", "tools")],
     variables=commonvars,
 
diff --git a/platformio/builder/scripts/atmelavr.py b/platformio/builder/scripts/atmelavr.py
index b3070b95..0c740e83 100644
--- a/platformio/builder/scripts/atmelavr.py
+++ b/platformio/builder/scripts/atmelavr.py
@@ -26,6 +26,7 @@ env.Replace(
     ARFLAGS=["rcs"],
 
     ASFLAGS=[
+        "-c",
         "-g",  # include debugging info (so errors include line numbers)
         "-x", "assembler-with-cpp",
         "-mmcu=$BOARD_MCU"
@@ -62,13 +63,14 @@ env.Replace(
         "-q",  # suppress progress output
         "-D",  # disable auto erase for flash memory
         "-p", "$BOARD_MCU",
-        "-C", join("$PIOPACKAGES_DIR", "tool-avrdude", "avrdude.conf"),
+        "-C", '"%s"' % join("$PIOPACKAGES_DIR",
+                            "tool-avrdude", "avrdude.conf"),
         "-c", "$UPLOAD_PROTOCOL",
         "-b", "$UPLOAD_SPEED",
         "-P", "$UPLOAD_PORT"
     ],
-    UPLOADHEXCMD="$UPLOADER $UPLOADERFLAGS -U flash:w:$SOURCES:i",
-    UPLOADEEPCMD="$UPLOADER $UPLOADERFLAGS -U eeprom:w:$SOURCES:i"
+    UPLOADHEXCMD='"$UPLOADER" $UPLOADERFLAGS -U flash:w:$SOURCES:i',
+    UPLOADEEPCMD='"$UPLOADER" $UPLOADERFLAGS -U eeprom:w:$SOURCES:i'
 )
 
 env.Append(
diff --git a/platformio/builder/scripts/frameworks/arduino.py b/platformio/builder/scripts/frameworks/arduino.py
index ca7409eb..34e12edd 100644
--- a/platformio/builder/scripts/frameworks/arduino.py
+++ b/platformio/builder/scripts/frameworks/arduino.py
@@ -56,4 +56,4 @@ libs.append(env.BuildLibrary(
     join("$PLATFORMFW_DIR", "cores", "${BOARD_OPTIONS['build']['core']}")
 ))
 
-Return("libs")
+Return("env libs")
diff --git a/platformio/builder/scripts/frameworks/energia.py b/platformio/builder/scripts/frameworks/energia.py
index 8c479287..5ad12955 100644
--- a/platformio/builder/scripts/frameworks/energia.py
+++ b/platformio/builder/scripts/frameworks/energia.py
@@ -44,4 +44,4 @@ libs.append(env.BuildLibrary(
     join("$PLATFORMFW_DIR", "cores", "${BOARD_OPTIONS['build']['core']}")
 ))
 
-Return("libs")
+Return("env libs")
diff --git a/platformio/builder/scripts/timsp430.py b/platformio/builder/scripts/timsp430.py
index 5af0f0c8..8899d474 100644
--- a/platformio/builder/scripts/timsp430.py
+++ b/platformio/builder/scripts/timsp430.py
@@ -25,6 +25,7 @@ env.Replace(
     ARFLAGS=["rcs"],
 
     ASFLAGS=[
+        "-c",
         "-g",  # include debugging info (so errors include line numbers)
         "-x", "-assembler-with-cpp",
         "-mmcu=$BOARD_MCU"
diff --git a/platformio/builder/scripts/titiva.py b/platformio/builder/scripts/titiva.py
index 4c7b06d8..12229da5 100644
--- a/platformio/builder/scripts/titiva.py
+++ b/platformio/builder/scripts/titiva.py
@@ -24,6 +24,7 @@ env.Replace(
     ARFLAGS=["rcs"],
 
     ASFLAGS=[
+        "-c",
         "-g",  # include debugging info (so errors include line numbers)
         "-x", "assembler-with-cpp",
         "-Wall",
diff --git a/platformio/builder/tools/platformio.py b/platformio/builder/tools/platformio.py
index 71feb13d..7f6ceb08 100644
--- a/platformio/builder/tools/platformio.py
+++ b/platformio/builder/tools/platformio.py
@@ -24,10 +24,11 @@ def ProcessGeneral(env):
             env.ConvertInoToCpp()
         for f in env['FRAMEWORK'].split(","):
             SConscriptChdir(0)
-            corelibs = SConscript(
+            env, libs = SConscript(
                 env.subst(join("$PIOBUILDER_DIR", "scripts",
                                "frameworks", "%s.py" % f.strip().lower())),
                 exports="env")
+            corelibs += libs
     return corelibs
 
 
@@ -74,13 +75,18 @@ def VariantDirRecursive(env, variant_dir, src_dir, duplicate=True,
     return variants
 
 
-def BuildLibrary(env, variant_dir, library_dir):
+def BuildLibrary(env, variant_dir, library_dir, ignore_files=None):
     lib = env.Clone()
     vdirs = lib.VariantDirRecursive(
         variant_dir, library_dir, ignore_pattern=(".git", ".svn", "examples"))
+    srcfiles = []
+    for vdir in vdirs:
+        for item in lib.GlobCXXFiles(vdir):
+            if not ignore_files or item.name not in ignore_files:
+                srcfiles.append(item)
     return lib.Library(
         lib.subst(variant_dir),
-        [lib.GlobCXXFiles(vdir) for vdir in vdirs]
+        srcfiles
     )