diff --git a/tests/tests.py b/tests/tests.py
index 0fbba37..cf88146 100755
--- a/tests/tests.py
+++ b/tests/tests.py
@@ -23,8 +23,6 @@
 from sqlalchemy.schema import Table
 from wtforms import fields
 from wtforms import Form
-from wtforms.compat import iteritems
-from wtforms.compat import text_type
 from wtforms.validators import InputRequired
 from wtforms.validators import Optional
 from wtforms.validators import Regexp
@@ -36,14 +34,13 @@
 class LazySelect:
     def __call__(self, field, **kwargs):
         return list(
-            (val, text_type(label), selected)
-            for val, label, selected in field.iter_choices()
+            (val, str(label), selected) for val, label, selected in field.iter_choices()
         )
 
 
 class Base:
     def __init__(self, **kwargs):
-        for k, v in iteritems(kwargs):
+        for k, v in iter(kwargs.items()):
             setattr(self, k, v)
 
 
diff --git a/wtforms_sqlalchemy/fields.py b/wtforms_sqlalchemy/fields.py
index d485733..d377fcf 100644
--- a/wtforms_sqlalchemy/fields.py
+++ b/wtforms_sqlalchemy/fields.py
@@ -4,8 +4,6 @@
 import operator
 
 from wtforms import widgets
-from wtforms.compat import string_types
-from wtforms.compat import text_type
 from wtforms.fields import SelectFieldBase
 from wtforms.validators import ValidationError
 
@@ -83,7 +81,7 @@ def __init__(
 
         if get_label is None:
             self.get_label = lambda x: x
-        elif isinstance(get_label, string_types):
+        elif isinstance(get_label, str):
             self.get_label = operator.attrgetter(get_label)
         else:
             self.get_label = get_label
@@ -111,7 +109,7 @@ def _get_object_list(self):
         if self._object_list is None:
             query = self.query if self.query is not None else self.query_factory()
             get_pk = self.get_pk
-            self._object_list = list((text_type(get_pk(obj)), obj) for obj in query)
+            self._object_list = list((str(get_pk(obj)), obj) for obj in query)
         return self._object_list
 
     def iter_choices(self):
@@ -215,4 +213,4 @@ class QueryCheckboxField(QuerySelectMultipleField):
 
 def get_pk_from_identity(obj):
     key = identity_key(instance=obj)[1]
-    return ":".join(text_type(x) for x in key)
+    return ":".join(str(x) for x in key)