diff --git a/tools/constraints-bionic.txt b/tools/constraints-bionic.txt
index f7b0c65528..30e78ec08e 100644
--- a/tools/constraints-bionic.txt
+++ b/tools/constraints-bionic.txt
@@ -2,6 +2,7 @@ attrs==17.4
 flake8==3.5.0
 py==1.5.2
 pycodestyle==2.3.1
+pyflakes==2.2.0
 pytest==3.3.2
 pytest-cov==2.5.1
 pyyaml==3.12
diff --git a/tools/constraints-xenial.txt b/tools/constraints-xenial.txt
index 81c4afc6a4..8dbceb1115 100644
--- a/tools/constraints-xenial.txt
+++ b/tools/constraints-xenial.txt
@@ -2,6 +2,7 @@ attrs==15.2
 flake8==2.5.4
 pep8==1.7.0
 py==1.4.31
+pyflakes==2.2.0
 pytest==2.8.7
 pytest-cov==2.2.1
 pyyaml==3.11