diff --git a/test-requirements.txt b/test-requirements.txt
index ab91e1c71b..735167c274 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -14,6 +14,9 @@ python-ironicclient>=0.8.0
 python-subunit>=0.0.18
 requests-mock>=0.6.0 # Apache-2.0
 sphinx!=1.2.0,!=1.3b1,<1.3,>=1.1.2
+# NOTE(tonyb): Pillow isn't used directly by nova but it's needed for
+# sphinxcontrib-seqdiag.  Make sure we honnor g-r caps
+Pillow>=2.4.0,<3.0.0 # MIT
 sphinxcontrib-seqdiag
 oslosphinx>=2.5.0 # Apache-2.0
 oslotest>=1.10.0 # Apache-2.0