diff --git a/requirements.txt b/requirements.txt
index f71732b9408956a5cac6709a0079630222d20fde..fe8a629b9a049938e04c73d9c49034b19bffc522 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,7 @@
 future
 dynesty
 corner
-numpy
+numpy>=1.9
 matplotlib>=2.0
 scipy
 gwpy