diff --git a/docs/rtd-pip-requirements b/docs/rtd-pip-requirements
index 46cbaa07..39619185 100644
--- a/docs/rtd-pip-requirements
+++ b/docs/rtd-pip-requirements
@@ -1,5 +1,5 @@
 stsci_rtd_theme
-numpy
+numpy >= 1.13
 matplotlib
 Cython
 astropy-helpers