diff --git a/Lib/test/test_xmlrpc.py b/Lib/test/test_xmlrpc.py
index 87bfb1f..f179df9 100644
--- a/Lib/test/test_xmlrpc.py
+++ b/Lib/test/test_xmlrpc.py
@@ -22,6 +22,7 @@ else:
     have_unicode = True
 
 alist = [{'astring': 'foo@bar.baz.spam',
+          'bstring': ''.join(map(chr,xrange(256))),
           'afloat': 7283.43,
           'anint': 2**20,
           'ashortlong': 2L,
diff --git a/Lib/xmlrpclib.py b/Lib/xmlrpclib.py
index c7971cc..535652d 100644
--- a/Lib/xmlrpclib.py
+++ b/Lib/xmlrpclib.py
@@ -690,9 +690,14 @@ class Marshaller:
     dispatch[FloatType] = dump_double
 
     def dump_string(self, value, write, escape=escape):
-        write("<value><string>")
-        write(escape(value))
-        write("</string></value>\n")
+        if all(32 <= ord(byte) <= 127 for byte in value):
+            write("<value><string>")
+            write(escape(value))
+            write("</string></value>\n")
+        else:
+            write("<value><base64>\n")
+            write(base64.b64encode(value))
+            write("</base64></value>\n")
     dispatch[StringType] = dump_string
 
     if unicode: