diff --git a/doc-requirements.txt b/doc-requirements.txt
index a356ee9..a0e7c0f 100644
--- a/doc-requirements.txt
+++ b/doc-requirements.txt
@@ -3,3 +3,8 @@ setuptools>=23.0.0
 sphinxcontrib-programoutput
 repoze.sphinx.autointerface
 sphinx_rtd_theme
+# RTD runs us on on alder Python 2.7, but
+# ZEO >= 5.0b1 needs at least 2.7.9. So pin
+# *both* ZODB and ZEO to older versions
+ZODB < 5
+ZEO < 5