diff --git a/lower-constraints.txt b/lower-constraints.txt
index a02749a9..55560564 100644
--- a/lower-constraints.txt
+++ b/lower-constraints.txt
@@ -3,6 +3,7 @@ cryptography===2.1
 fixtures===3.0.0
 openstackdocstheme==1.18.1
 oslotest===3.2.0
+python-dateutil==2.8.1
 python-subunit===1.0.0
 Sphinx===1.6.5
 stestr==1.0.0
diff --git a/requirements.txt b/requirements.txt
index 1fb58a99..a2feeaa8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,2 @@
 cryptography>=2.1  # BSD/Apache-2.0
+python-dateutil>=2.8.1  # BSD