diff --git a/PIL/ImageMode.py b/PIL/ImageMode.py
index 91fd0fdca..b227f2127 100644
--- a/PIL/ImageMode.py
+++ b/PIL/ImageMode.py
@@ -14,7 +14,7 @@
 #
 
 # mode descriptor cache
-_modes = {}
+_modes = None
 
 
 class ModeDescriptor(object):
@@ -32,19 +32,24 @@ class ModeDescriptor(object):
 
 def getmode(mode):
     """Gets a mode descriptor for the given mode."""
+    global _modes
     if not _modes:
         # initialize mode cache
+
         from . import Image
+        modes = {}
         # core modes
         for m, (basemode, basetype, bands) in Image._MODEINFO.items():
-            _modes[m] = ModeDescriptor(m, bands, basemode, basetype)
+            modes[m] = ModeDescriptor(m, bands, basemode, basetype)
         # extra experimental modes
-        _modes["RGBa"] = ModeDescriptor("RGBa", ("R", "G", "B", "a"), "RGB", "L")
-        _modes["LA"] = ModeDescriptor("LA", ("L", "A"), "L", "L")
-        _modes["La"] = ModeDescriptor("La", ("L", "a"), "L", "L")
-        _modes["PA"] = ModeDescriptor("PA", ("P", "A"), "RGB", "L")
+        modes["RGBa"] = ModeDescriptor("RGBa", ("R", "G", "B", "a"), "RGB", "L")
+        modes["LA"] = ModeDescriptor("LA", ("L", "A"), "L", "L")
+        modes["La"] = ModeDescriptor("La", ("L", "a"), "L", "L")
+        modes["PA"] = ModeDescriptor("PA", ("P", "A"), "RGB", "L")
         # mapping modes
-        _modes["I;16"] = ModeDescriptor("I;16", "I", "L", "L")
-        _modes["I;16L"] = ModeDescriptor("I;16L", "I", "L", "L")
-        _modes["I;16B"] = ModeDescriptor("I;16B", "I", "L", "L")
+        modes["I;16"] = ModeDescriptor("I;16", "I", "L", "L")
+        modes["I;16L"] = ModeDescriptor("I;16L", "I", "L", "L")
+        modes["I;16B"] = ModeDescriptor("I;16B", "I", "L", "L")
+        # set global mode cache atomically
+        _modes = modes
     return _modes[mode]
diff --git a/depends/install_imagequant.sh b/depends/install_imagequant.sh
index 21386557b..4a8c0e6be 100755
--- a/depends/install_imagequant.sh
+++ b/depends/install_imagequant.sh
@@ -1,14 +1,14 @@
 #!/bin/bash
 # install libimagequant
 
-archive=pngquant-2.8.2
+archive=libimagequant-2.8.2
 
 ./download-and-extract.sh $archive https://raw.githubusercontent.com/python-pillow/pillow-depends/master/$archive.tar.gz
 
 pushd $archive
 
-make -C lib shared
-sudo cp lib/libimagequant.so* /usr/lib/
-sudo cp lib/libimagequant.h /usr/include/
+make shared
+sudo cp libimagequant.so* /usr/lib/
+sudo cp libimagequant.h /usr/include/
 
 popd
diff --git a/winbuild/build.py b/winbuild/build.py
index 487977adb..1fbfa14a6 100644
--- a/winbuild/build.py
+++ b/winbuild/build.py
@@ -16,7 +16,7 @@ def setup_vms():
         for arch in ('', X64_EXT):
             ret.append("virtualenv -p c:/Python%s%s/python.exe --clear %s%s%s"
                        % (py, arch, VIRT_BASE, py, arch))
-            ret.append("%s%s%s\Scripts\pip.exe install nose" %
+            ret.append(r"%s%s%s\Scripts\pip.exe install nose" %
                        (VIRT_BASE, py, arch))
     return "\n".join(ret)
 
diff --git a/winbuild/build_dep.py b/winbuild/build_dep.py
index 4c397236b..fb4d55d8c 100644
--- a/winbuild/build_dep.py
+++ b/winbuild/build_dep.py
@@ -13,6 +13,7 @@ def _relpath(*args):
 def _relbuild(*args):
     return _relpath('build', *args)
 
+
 build_dir = _relpath('build')
 inc_dir = _relpath('depends')
 
@@ -108,7 +109,7 @@ set MSBUILD=C:\Windows\Microsoft.NET\Framework64\v4.0.30319\MSBuild.exe
 set CMAKE="cmake.exe"
 set INCLIB=%~dp0\depends
 set BUILD=%~dp0\build
-""" + "\n".join('set %s=%%BUILD%%\%s' % (k.upper(), v['dir'])
+""" + "\n".join(r'set %s=%%BUILD%%\%s' % (k.upper(), v['dir'])
                 for (k, v) in libs.items() if v['dir'])
 
 
diff --git a/winbuild/config.py b/winbuild/config.py
index 3cbba9d97..efe36810b 100644
--- a/winbuild/config.py
+++ b/winbuild/config.py
@@ -19,10 +19,10 @@ libs = {
     #     'version': '2.0'
     # },
     'zlib': {
-        'url': 'http://zlib.net/zlib128.zip',
-        'filename': PILLOW_DEPENDS_DIR + 'zlib128.zip',
-        'hash': 'md5:126f8676442ffbd97884eb4d6f32afb4',
-        'dir': 'zlib-1.2.8',
+        'url': 'http://zlib.net/zlib1210.zip',
+        'filename': PILLOW_DEPENDS_DIR + 'zlib1210.zip',
+        'hash': 'md5:5327bdff96926cf9c479008bae983bc0',
+        'dir': 'zlib-1.2.10',
     },
     'jpeg': {
         'url': 'http://www.ijg.org/files/jpegsr9b.zip',
@@ -37,10 +37,10 @@ libs = {
         'dir': 'tiff-4.0.6',
     },
     'freetype': {
-        'url': 'http://download.savannah.gnu.org/releases/freetype/freetype-2.7.tar.gz',
-        'filename': PILLOW_DEPENDS_DIR + 'freetype-2.7.tar.gz',
-        'hash': 'md5:337139e5c7c5bd645fe130608e0fa8b5',
-        'dir': 'freetype-2.7',
+        'url': 'http://download.savannah.gnu.org/releases/freetype/freetype-2.7.1.tar.gz',
+        'filename': PILLOW_DEPENDS_DIR + 'freetype-2.7.1.tar.gz',
+        'hash': 'md5:78701bee8d249578d83bb9a2f3aa3616',
+        'dir': 'freetype-2.7.1',
     },
     'lcms': {
         'url': SF_MIRROR+'/project/lcms/lcms/2.7/lcms2-2.7.zip',