diff --git a/Makefile b/Makefile
index 21fdc7b..7ff54e9 100644
--- a/Makefile
+++ b/Makefile
@@ -29,7 +29,7 @@ clean: pyclean docsclean
 	@rm -rf venv
 
 venv:
-	@python3.6 -m venv venv
+	@python3.8 -m venv venv
 	@$(PIP) install -U "pip>=7.0" -q
 	@$(PIP) install -r $(DEPS)
 
diff --git a/pkgversion/pkgversion.py b/pkgversion/pkgversion.py
index e781977..eb7fb41 100755
--- a/pkgversion/pkgversion.py
+++ b/pkgversion/pkgversion.py
@@ -5,9 +5,13 @@
 from subprocess import PIPE, Popen
 
 try:
-    from pip._internal.download import PipSession
-    from pip._internal.req import parse_requirements
-except ImportError:
+    try:  # pip20+
+        from pip._internal.network.session import PipSession
+        from pip._internal.req import parse_requirements
+    except:  # pip10+
+        from pip._internal.download import PipSession
+        from pip._internal.req import parse_requirements
+except ImportError:  # pip<10
     # Output expected ImportErrors for PIP < 10.
     from pip.download import PipSession
     from pip.req import parse_requirements
diff --git a/tox.ini b/tox.ini
index 56ed732..f5605c2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,6 +6,7 @@ envlist =
     py27-{pip9,pip10}
     py35-{pip9,pip10}
     py36-{pip9,pip10}
+    py38-pip20
     cov
     isort-check
     isort-fix
@@ -14,68 +15,53 @@ envlist =
 
 skipsdist = true
 
+[testenv]
 basepython =
-    py27-{pip9,pip10}: python2.7
-    py35-{pip9,pip10}: python3.5
-    py36-{pip9,pip10}: python3.6
-    cov: python3.6
+    py27: python2.7
+    py35: python3.5
+    py36: python3.6
+    py38: python3.8
+    cov: python3.8
 deps =
     -rrequirements/requirements-base.txt
     -rrequirements/requirements-testing.txt
+    pip9: pip<10.0
+    pip10: pip<11.0
+    pip20: pip<21.0
+commands =
+     py.test tests
 
 [testenv:cov]
-basepython= python3.6
+basepython= python3.8
 commands =
     py.test tests --cov-report=term-missing --cov-append --cov=pkgversion --cov-report xml {posargs}
 deps =
     -rrequirements/requirements-base.txt
     -rrequirements/requirements-testing.txt
 
-[general]
-commands =
-     py.test tests
-deps =
-    -rrequirements/requirements-base.txt
-    -rrequirements/requirements-testing.txt
-
-[testenv:py27-{pip9,pip10}]
-basepython = python2.7
-commands =
-    {[general]commands}
-
-[testenv:py35-{pip9,pip10}]
-basepython = python3.5
-commands =
-   {[general]commands}
-
-[testenv:py36-{pip9,pip10}]
-basepython = python3.6
-commands =
-    {[general]commands}
-
 ##
 # Flake8 linting
 ##
 
 [testenv:lint]
-basepython = python3.6
+basepython = python3.8
 commands = flake8 pkgversion tests --exclude=pkgversion/__init__.py
 deps =
     flake8
 
 [testenv:docs]
-basepython = python3.6
+basepython = python3.8
 commands = sphinx-build -W -b html {toxinidir}/docs {toxinidir}/docs/_build/html
 deps =
     -rrequirements/requirements-testing.txt
 
 [testenv:isort-check]
-basepython = python3.6
+basepython = python3.8
 commands = isort -rc -c pkgversion tests
 deps = isort
 
 [testenv:isort-fix]
-basepython = python3.6
+basepython = python3.8
 commands = isort -rc pkgversion tests
 deps = isort