diff --git a/MANIFEST.in b/MANIFEST.in
index df58cf3..bf15100 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -2,6 +2,7 @@ include *.sh *.py *.bat 8.txt *.md
 include *.h
 include LICENSE.txt
 recursive-include nng *
+recursive-include mbedtls *
 recursive-include test *.py
 recursive-include pynng *.py
 prune nng/build
diff --git a/pynng/_version.py b/pynng/_version.py
index eb6ad29..42065f4 100644
--- a/pynng/_version.py
+++ b/pynng/_version.py
@@ -1,3 +1,3 @@
 # This file is imported from __init__.py and exec'd from setup.py
 
-__version__ = "0.6.1"
+__version__ = "0.6.2"
diff --git a/setup.py b/setup.py
index edbdba4..46c3a11 100644
--- a/setup.py
+++ b/setup.py
@@ -34,12 +34,11 @@ def build_mbedtls(cmake_args):
 
     """
     do = check_call
-    if os.path.exists('mbedtls'):
-        _rmdir('mbedtls')
-    do('git clone --recursive {}'.format(MBEDTLS_REPO), shell=True)
-    # for local hacking, just copy a directory (network connection is slow)
-    # do('cp -r ../mbedtls mbedtls', shell=True)
-    do('git checkout {}'.format(MBEDTLS_REV), shell=True, cwd='mbedtls')
+    if not os.path.exists('mbedtls'):
+        do('git clone --recursive {}'.format(MBEDTLS_REPO), shell=True)
+        # for local hacking, just copy a directory (network connection is slow)
+        # do('cp -r ../mbedtls mbedtls', shell=True)
+        do('git checkout {}'.format(MBEDTLS_REV), shell=True, cwd='mbedtls')
     cwd = 'mbedtls/build'
     os.mkdir(cwd)
     cmake_cmd = ['cmake'] + cmake_args
@@ -64,12 +63,11 @@ def build_nng(cmake_args):
 
     """
     do = check_call
-    if os.path.exists('nng'):
-        _rmdir('nng')
-    do('git clone {}'.format(NNG_REPO), shell=True)
-    # for local hacking, just copy a directory (network connection is slow)
-    # do('cp -r ../nng-clean nng', shell=True)
-    do('git checkout {}'.format(NNG_REV), shell=True, cwd='nng')
+    if not os.path.exists('nng'):
+        do('git clone {}'.format(NNG_REPO), shell=True)
+        # for local hacking, just copy a directory (network connection is slow)
+        # do('cp -r ../nng-clean nng', shell=True)
+        do('git checkout {}'.format(NNG_REV), shell=True, cwd='nng')
     os.mkdir('nng/build')
     cmake_cmd = ['cmake'] + cmake_args
     cmake_cmd += [