diff --git a/speedtest.py b/speedtest.py
index 7ea05a5..0fe067b 100755
--- a/speedtest.py
+++ b/speedtest.py
@@ -70,6 +70,7 @@ except ImportError:
         import xml.etree.ElementTree as ET
     except ImportError:
         from xml.dom import minidom as DOM
+        from xml.parsers.expat import ExpatError
         ET = None
 
 try:
@@ -284,7 +285,11 @@ class SpeedtestHTTPError(SpeedtestException):
 
 
 class SpeedtestConfigError(SpeedtestException):
-    """Configuration provided is invalid"""
+    """Configuration XML is invalid"""
+
+
+class SpeedtestServersError(SpeedtestException):
+    """Servers XML is invalid"""
 
 
 class ConfigRetrievalError(SpeedtestHTTPError):
@@ -1042,16 +1047,16 @@ class Speedtest(object):
         uh, e = catch_request(request, opener=self._opener)
         if e:
             raise ConfigRetrievalError(e)
-        configxml = []
+        configxml_list = []
 
         stream = get_response_stream(uh)
 
         while 1:
             try:
-                configxml.append(stream.read(1024))
+                configxml_list.append(stream.read(1024))
             except (OSError, EOFError):
                 raise ConfigRetrievalError(get_exception())
-            if len(configxml[-1]) == 0:
+            if len(configxml_list[-1]) == 0:
                 break
         stream.close()
         uh.close()
@@ -1059,10 +1064,18 @@ class Speedtest(object):
         if int(uh.code) != 200:
             return None
 
-        printer('Config XML:\n%s' % ''.encode().join(configxml), debug=True)
+        configxml = ''.encode().join(configxml_list)
+
+        printer('Config XML:\n%s' % configxml, debug=True)
 
         try:
-            root = ET.fromstring(''.encode().join(configxml))
+            try:
+                root = ET.fromstring(configxml)
+            except ET.ParseError:
+                e = get_exception()
+                raise SpeedtestConfigError(
+                    'Malformed speedtest.net configuration: %s' % e
+                )
             server_config = root.find('server-config').attrib
             download = root.find('download').attrib
             upload = root.find('upload').attrib
@@ -1070,7 +1083,13 @@ class Speedtest(object):
             client = root.find('client').attrib
 
         except AttributeError:
-            root = DOM.parseString(''.join(configxml))
+            try:
+                root = DOM.parseString(configxml)
+            except ExpatError:
+                e = get_exception()
+                raise SpeedtestConfigError(
+                    'Malformed speedtest.net configuration: %s' % e
+                )
             server_config = get_attributes_by_tag_name(root, 'server-config')
             download = get_attributes_by_tag_name(root, 'download')
             upload = get_attributes_by_tag_name(root, 'upload')
@@ -1179,13 +1198,13 @@ class Speedtest(object):
 
                 stream = get_response_stream(uh)
 
-                serversxml = []
+                serversxml_list = []
                 while 1:
                     try:
-                        serversxml.append(stream.read(1024))
+                        serversxml_list.append(stream.read(1024))
                     except (OSError, EOFError):
                         raise ServersRetrievalError(get_exception())
-                    if len(serversxml[-1]) == 0:
+                    if len(serversxml_list[-1]) == 0:
                         break
 
                 stream.close()
@@ -1194,15 +1213,28 @@ class Speedtest(object):
                 if int(uh.code) != 200:
                     raise ServersRetrievalError()
 
-                printer('Servers XML:\n%s' % ''.encode().join(serversxml),
-                        debug=True)
+                serversxml = ''.encode().join(serversxml_list)
+
+                printer('Servers XML:\n%s' % serversxml, debug=True)
 
                 try:
                     try:
-                        root = ET.fromstring(''.encode().join(serversxml))
+                        try:
+                            root = ET.fromstring(serversxml)
+                        except ET.ParseError:
+                            e = get_exception()
+                            raise SpeedtestServersError(
+                                'Malformed speedtest.net server list: %s' % e
+                            )
                         elements = root.getiterator('server')
                     except AttributeError:
-                        root = DOM.parseString(''.join(serversxml))
+                        try:
+                            root = DOM.parseString(serversxml)
+                        except ExpatError:
+                            e = get_exception()
+                            raise SpeedtestServersError(
+                                'Malformed speedtest.net server list: %s' % e
+                            )
                         elements = root.getElementsByTagName('server')
                 except (SyntaxError, xml.parsers.expat.ExpatError):
                     raise ServersRetrievalError()