diff --git a/paramiko/file.py b/paramiko/file.py
index 253ffcd..571ee6e 100644
--- a/paramiko/file.py
+++ b/paramiko/file.py
@@ -436,7 +436,7 @@ class BufferedFile (object):
             return
         if self.newlines is None:
             self.newlines = newline
-        elif (type(self.newlines) is str) and (self.newlines != newline):
+        elif isinstance(self.newlines, basestring) and (self.newlines != newline):
             self.newlines = (self.newlines, newline)
         elif newline not in self.newlines:
             self.newlines += (newline,)
diff --git a/paramiko/server.py b/paramiko/server.py
index bf11cda..bec08fc 100644
--- a/paramiko/server.py
+++ b/paramiko/server.py
@@ -514,7 +514,7 @@ class InteractiveQuery (object):
         self.instructions = instructions
         self.prompts = []
         for x in prompts:
-            if (type(x) is str) or (type(x) is unicode):
+            if isinstance(x, basestring):
                 self.add_prompt(x)
             else:
                 self.add_prompt(x[0], x[1])
diff --git a/paramiko/sftp_client.py b/paramiko/sftp_client.py
index 0580bc4..13e830c 100644
--- a/paramiko/sftp_client.py
+++ b/paramiko/sftp_client.py
@@ -660,7 +660,7 @@ class SFTPClient(BaseSFTP):
                     msg.add_int(item)
                 elif isinstance(item, long):
                     msg.add_int64(item)
-                elif isinstance(item, str):
+                elif isinstance(item, basestring):
                     msg.add_string(item)
                 elif isinstance(item, SFTPAttributes):
                     item._pack(msg)
diff --git a/sites/www/changelog.rst b/sites/www/changelog.rst
index 720d93a..eaf7444 100644
--- a/sites/www/changelog.rst
+++ b/sites/www/changelog.rst
@@ -2,6 +2,9 @@
 Changelog
 =========
 
+* :bug:`235` Improve string type testing in a handful of spots (e.g. ``s/if
+  type(x) is str/if isinstance(x, basestring)/g``.) Thanks to ``@ksamuel`` for
+  the report.
 * :release:`1.12.3 <2014-03-13>`
 * :release:`1.11.5 <2014-03-13>`
 * :release:`1.10.7 <2014-03-13>`