diff --git a/requirements.txt b/requirements.txt
index c0f541d9..441d8d5a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,7 @@ scipy
 numpy
 pandas>=1.1
 llnl-hatchet
-extrap
+extrap==4.2.0
 matplotlib
 seaborn
 beautifulsoup4