diff --git a/sasl/saslwrapper.pyx b/sasl/saslwrapper.pyx
index ef5ab7e..f754e38 100644
--- a/sasl/saslwrapper.pyx
+++ b/sasl/saslwrapper.pyx
@@ -14,8 +14,6 @@
 
 #cython: language_level=3
 
-from six import string_types, PY3
-
 from libcpp cimport bool
 from libc.stdint cimport uint32_t
 from libcpp.string cimport string as string_t
@@ -36,7 +34,7 @@ cdef extern from 'saslwrapper.h' namespace 'saslwrapper':
 
 
 cpdef string_t to_bytes(bytes_or_str):
-    if PY3 and isinstance(bytes_or_str, string_types):
+    if isinstance(bytes_or_str, str):
         return bytes_or_str.encode('utf-8')
     return bytes_or_str
 
@@ -53,7 +51,7 @@ cdef class Client:
     cpdef setAttr(self, key, value):
         if isinstance(value, int):
             return self._this.setAttr(to_bytes(key), <uint32_t> value)
-        elif isinstance(value, string_types):
+        elif isinstance(value, str):
             return self._this.setAttr(to_bytes(key), <string_t> to_bytes(value))
 
     cpdef init(self):