diff --git a/requirements.txt b/requirements.txt
index 13f4bb35a3d1d7fb1929615940f7f04d8d5224a5..845231f285d643ed0697de8bdc84caabf16ae374 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -9,4 +9,4 @@ scipy==1.7.0
 
 python-constraint==1.4.0
 unified-planning==0.6.0
-up-pyperplan==2.1
+up-pyperplan==1.0.0