diff --git a/test-requirements.txt b/test-requirements.txt
index f0211ee79..69b2c312c 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -8,5 +8,10 @@ Pygments
 # At least 1.3 is required for dedent in code blocks. Capped to 1.3 to not get an automatic update to any newer versions.
 sphinx>=1.3,!=1.3b1,<1.4
 openstackdocstheme>=1.0.7
+# NOTE(tonyb) Pillow isn't directly needed but it's pulled in via
+# Collecting Pillow (from blockdiag>=1.5.0->nwdiag
+# So cap as per global-requirements until https://launchpad.net/bugs/1501995
+# is properly fixed
+Pillow>=2.4.0,<3.0.0 # MIT
 nwdiag
 sphinxcontrib-nwdiag