diff --git a/.travis.yml b/.travis.yml
index 702140e92..341ad2f6a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,5 @@
 language: python
 python:
-  - "3.5"
   - "3.6"
   - "3.7"
   - "3.8"
diff --git a/owslib/feature/common.py b/owslib/feature/common.py
index e787bde71..e097c793a 100644
--- a/owslib/feature/common.py
+++ b/owslib/feature/common.py
@@ -1,21 +1,9 @@
-from io import StringIO
 from owslib.etree import etree
 from owslib.util import Authentication, openURL
 
 from urllib.parse import urlencode, parse_qsl
 
 
-def makeStringIO(strval):
-    """
-    Helper method to make sure the StringIO being returned will work.
-
-    Differences between Python 2.7/3.x mean we have a lot of cases to handle.
-
-    TODO: skipped Python 2.x support. Is this still necessary?
-    """
-    return StringIO(strval.decode())
-
-
 class WFSCapabilitiesReader(object):
     """Read and parse capabilities document into a lxml.etree infoset
     """
diff --git a/owslib/feature/wfs100.py b/owslib/feature/wfs100.py
index f07f413ae..8ba35b792 100644
--- a/owslib/feature/wfs100.py
+++ b/owslib/feature/wfs100.py
@@ -8,6 +8,7 @@
 
 from owslib import util
 
+from io import BytesIO
 from urllib.parse import urlencode
 from owslib.util import (
     testXMLValue,
@@ -27,7 +28,6 @@
 from owslib.feature.common import (
     WFSCapabilitiesReader,
     AbstractContentMetadata,
-    makeStringIO,
 )
 
 import pyproj
@@ -308,16 +308,16 @@ def getfeature(
                 tree = etree.fromstring(data)
             except BaseException:
                 # Not XML
-                return makeStringIO(data)
+                return BytesIO(data)
             else:
                 if tree.tag == "{%s}ServiceExceptionReport" % OGC_NAMESPACE:
                     se = tree.find(nspath("ServiceException", OGC_NAMESPACE))
                     raise ServiceException(str(se.text).strip())
                 else:
-                    return makeStringIO(data)
+                    return BytesIO(data)
         else:
             if have_read:
-                return makeStringIO(data)
+                return BytesIO(data)
             return u
 
     def getOperationByName(self, name):
diff --git a/owslib/feature/wfs110.py b/owslib/feature/wfs110.py
index 7e483ff8b..34db9ed4e 100644
--- a/owslib/feature/wfs110.py
+++ b/owslib/feature/wfs110.py
@@ -7,6 +7,7 @@
 # Contact email: tomkralidis@gmail.com
 # =============================================================================
 
+from io import BytesIO
 from urllib.parse import urlencode
 from owslib.util import (
     testXMLValue,
@@ -33,7 +34,6 @@
 from owslib.feature.common import (
     WFSCapabilitiesReader,
     AbstractContentMetadata,
-    makeStringIO,
 )
 from owslib.namespaces import Namespaces
 from owslib.util import log, openURL
@@ -346,16 +346,16 @@ def getfeature(
                 tree = etree.fromstring(data)
             except BaseException:
                 # Not XML
-                return makeStringIO(data)
+                return BytesIO(data)
             else:
                 if tree.tag == "{%s}ServiceExceptionReport" % namespaces["ogc"]:
                     se = tree.find(nspath_eval("ServiceException", namespaces["ogc"]))
                     raise ServiceException(str(se.text).strip())
                 else:
-                    return makeStringIO(data)
+                    return BytesIO(data)
         else:
             if have_read:
-                return makeStringIO(data)
+                return BytesIO(data)
             return u
 
     def getOperationByName(self, name):
diff --git a/owslib/feature/wfs200.py b/owslib/feature/wfs200.py
index 53214defc..4951aab02 100644
--- a/owslib/feature/wfs200.py
+++ b/owslib/feature/wfs200.py
@@ -18,11 +18,11 @@
 from owslib.feature.common import (
     WFSCapabilitiesReader,
     AbstractContentMetadata,
-    makeStringIO,
 )
 from owslib.namespaces import Namespaces
 
 # other imports
+from io import BytesIO
 from urllib.parse import urlencode
 
 import logging
@@ -313,16 +313,16 @@ def getfeature(
                 tree = etree.fromstring(data)
             except BaseException:
                 # Not XML
-                return makeStringIO(data)
+                return BytesIO(data)
             else:
                 if tree.tag == "{%s}ServiceExceptionReport" % OGC_NAMESPACE:
                     se = tree.find(nspath("ServiceException", OGC_NAMESPACE))
                     raise ServiceException(str(se.text).strip())
                 else:
-                    return makeStringIO(data)
+                    return BytesIO(data)
         else:
             if have_read:
-                return makeStringIO(data)
+                return BytesIO(data)
             return u
 
     def getpropertyvalue(
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 2aa2a0a6b..11e2eef86 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -4,7 +4,3 @@ pytest>=3.6
 pytest-cov
 Pillow
 tox
-# install libraries to stop SSL related InsecurePlatformWarning
-pyopenssl        ; python_version < '2.7.9'
-ndg-httpsclient  ; python_version < '2.7.9'
-pyasn1           ; python_version < '2.7.9'
diff --git a/setup.py b/setup.py
index 7061a353a..3543bdbc3 100644
--- a/setup.py
+++ b/setup.py
@@ -28,7 +28,7 @@ def run_tests(self):
       maintainer_email  = 'tomkralidis@gmail.com',
       url               = 'https://geopython.github.io/OWSLib',
       install_requires  = reqs,
-      python_requires   = '>=3.5',
+      python_requires   = '>=3.6',
       cmdclass          = {'test': PyTest},
       packages          = find_packages(exclude=["docs", "etc", "examples", "tests"]),
       classifiers       = [
diff --git a/tests/doctests/wfs_MapServerWFSFeature.txt b/tests/doctests/wfs_MapServerWFSFeature.txt
index cf62a3be4..50cf899ad 100644
--- a/tests/doctests/wfs_MapServerWFSFeature.txt
+++ b/tests/doctests/wfs_MapServerWFSFeature.txt
@@ -7,7 +7,7 @@ Test the getfeature method
 
     >>> wfs = WebFeatureService('http://nsidc.org/cgi-bin/atlas_south?', version='1.0.0')
     >>> response = wfs.getfeature(typename=['glaciers'], maxfeatures=5)
-    >>> response.read().find('<wfs:FeatureCollection') > 0
+    >>> response.read().find(b'<wfs:FeatureCollection') > 0
     True
 
 Handle service exception