diff --git a/requirements/base.txt b/requirements/base.txt
index 3fd8d15..d8dc124 100644
--- a/requirements/base.txt
+++ b/requirements/base.txt
@@ -1,3 +1,3 @@
-setuptools
-jinja2
-appdirs
+setuptools==41.4.0
+jinja2==2.10.3
+appdirs==1.4.3
diff --git a/requirements/dev.txt b/requirements/dev.txt
index ad1bc21..a8de2d5 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -1,2 +1,2 @@
-bumpversion
-invoke
+bumpversion==0.5.3
+invoke==1.3.0
diff --git a/requirements/py2.txt b/requirements/py2.txt
index c7709d3..65093fc 100644
--- a/requirements/py2.txt
+++ b/requirements/py2.txt
@@ -1 +1 @@
-pathlib
+pathlib==1.0.1
diff --git a/requirements/test.txt b/requirements/test.txt
index b1cfae0..40beb5a 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -1,2 +1,2 @@
-testfixtures
-tox
+testfixtures==6.10.0
+tox==3.14.0