diff --git a/platformio/downloader.py b/platformio/downloader.py
index be5e8888..60f0e159 100644
--- a/platformio/downloader.py
+++ b/platformio/downloader.py
@@ -22,7 +22,6 @@ import click
 import requests
 
 from platformio import util
-from platformio.compat import PY2, get_filesystem_encoding
 from platformio.exception import (FDSHASumMismatch, FDSizeMismatch,
                                   FDUnrecognizedStatusCode)
 from platformio.proc import exec_command
@@ -46,15 +45,11 @@ class FileDownloader(object):
         if disposition and "filename=" in disposition:
             self._fname = disposition[disposition.index("filename=") +
                                       9:].replace('"', "").replace("'", "")
-            if PY2:
-                self._fname = self._fname.encode("utf8")
         else:
             self._fname = [p for p in url.split("/") if p][-1]
-
+        self._fname = str(self._fname)
         self._destination = self._fname
         if dest_dir:
-            if PY2:
-                dest_dir = dest_dir.decode(get_filesystem_encoding())
             self.set_destination(join(dest_dir, self._fname))
 
     def set_destination(self, destination):
diff --git a/platformio/managers/platform.py b/platformio/managers/platform.py
index e7a29027..2e4d2ebf 100644
--- a/platformio/managers/platform.py
+++ b/platformio/managers/platform.py
@@ -24,7 +24,8 @@ import click
 import semantic_version
 
 from platformio import __version__, app, exception, util
-from platformio.compat import get_filesystem_encoding, string_types
+from platformio.compat import (get_filesystem_encoding, hashlib_encode_data,
+                               is_bytes)
 from platformio.managers.core import get_core_package_dir
 from platformio.managers.package import BasePkgManager, PackageManager
 from platformio.proc import (BuildAsyncPipe, copy_pythonpath_to_osenv,
@@ -361,14 +362,13 @@ class PlatformRunMixin(object):
 
     @staticmethod
     def encode_scons_arg(value):
-        if isinstance(value, string_types):
-            value = value.encode(get_filesystem_encoding())
-        return base64.urlsafe_b64encode(value).decode()
+        data = base64.urlsafe_b64encode(hashlib_encode_data(value))
+        return data.decode() if is_bytes(data) else data
 
     @staticmethod
-    def decode_scons_arg(value):
-        return base64.urlsafe_b64decode(value).decode(
-            get_filesystem_encoding())
+    def decode_scons_arg(data):
+        value = base64.urlsafe_b64decode(data)
+        return value.decode() if is_bytes(value) else value
 
     def run(self, variables, targets, silent, verbose):
         assert isinstance(variables, dict)