diff --git a/flanker/mime/message/headers/wrappers.py b/flanker/mime/message/headers/wrappers.py
index 87aab05e..6e02a663 100644
--- a/flanker/mime/message/headers/wrappers.py
+++ b/flanker/mime/message/headers/wrappers.py
@@ -100,7 +100,11 @@ def get_boundary_line(self, final=False):
             self.get_boundary(), "--" if final else "")
 
     def get_charset(self):
-        return self.params.get("charset", 'ascii').lower()
+        default = 'ascii' if self.main == 'text' else None
+        c = self.params.get("charset", default)
+        if c:
+            c = c.lower()
+        return c
 
     def set_charset(self, value):
         self.params["charset"] = value.lower()
diff --git a/setup.py b/setup.py
index ed38ffb4..8ecbb10d 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 
 
 setup(name='flanker',
-      version='0.4.21',
+      version='0.4.22',
       description='Mailgun Parsing Tools',
       long_description=open('README.rst').read(),
       classifiers=[],
diff --git a/tests/mime/message/headers/wrappers_test.py b/tests/mime/message/headers/wrappers_test.py
new file mode 100644
index 00000000..e59c1dff
--- /dev/null
+++ b/tests/mime/message/headers/wrappers_test.py
@@ -0,0 +1,10 @@
+from nose.tools import eq_
+
+from flanker.mime.message.headers.wrappers import ContentType
+
+def charset_test():
+    c = ContentType('text', 'plain')
+    eq_('ascii', c.get_charset())
+
+    c = ContentType('application', 'pdf')
+    eq_(None, c.get_charset())