diff --git a/requirements.txt b/requirements.txt
index b23a792..013a520 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-numpy>=1.18.5
+numpy>=1.18.5,<2
 PyYAML>=5.3.1
 ruamel.yaml>=0.16.12
 igraph>=0.9