diff --git a/requirements-dev.txt b/requirements-dev.txt
index dac279a..461eb87 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -19,7 +19,7 @@ MarkupSafe==1.0          # via jinja2
 mccabe==0.6.1
 pep8-naming==0.4.1
 pep8==1.7.0               # via flake8
-pip-tools==1.8.2
+pip-tools==1.9.0
 pluggy==0.4.0 # via tox
 py==1.4.33 # via pytest, pytest-capturelog, tox
 pydocstyle==1.1.1