diff --git a/Lib/email/message.py b/Lib/email/message.py
index ff262c7..471d46b 100644
--- a/Lib/email/message.py
+++ b/Lib/email/message.py
@@ -20,18 +20,22 @@
 
 SEMISPACE = '; '
 
-# Regular expression used to split header parameters.  BAW: this may be too
-# simple.  It isn't strictly RFC 2045 (section 5.1) compliant, but it catches
-# most headers found in the wild.  We may eventually need a full fledged
-# parser eventually.
-paramre = re.compile(r'\s*;\s*')
 # Regular expression that matches `special' characters in parameters, the
 # existance of which force quoting of the parameter value.
 tspecials = re.compile(r'[ \(\)<>@,;:\\"/\[\]\?=]')
 
 
-
 # Helper functions
+def _splitparam(param):
+    # Split header parameters.  BAW: this may be too simple.  It isn't
+    # strictly RFC 2045 (section 5.1) compliant, but it catches most headers
+    # found in the wild.  We may eventually need a full fledged parser
+    # eventually.
+    a, sep, b = param.partition(';')
+    if not sep:
+        return a.strip(), None
+    return a.strip(), b.strip()
+
 def _formatparam(param, value=None, quote=True):
     """Convenience function to format and return a key=value pair.
 
@@ -443,7 +447,7 @@
         if value is missing:
             # This should have no parameters
             return self.get_default_type()
-        ctype = paramre.split(value)[0].lower().strip()
+        ctype = _splitparam(value)[0].lower()
         # RFC 2045, section 5.2 says if its invalid, use text/plain
         if ctype.count('/') != 1:
             return 'text/plain'
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index e4bc019..9e96e93 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -813,9 +813,14 @@
 
     def testzip(self):
         """Read all the files and check the CRC."""
+        chunk_size = 2 ** 20
         for zinfo in self.filelist:
             try:
-                self.read(zinfo.filename)       # Check CRC-32
+                # Read by chunks, to avoid an OverflowError or a
+                # MemoryError with very large embedded files.
+                f = self.open(zinfo.filename, "r")
+                while f.read(chunk_size):     # Check CRC-32
+                    pass
             except BadZipfile:
                 return zinfo.filename