diff --git a/requirements.txt b/requirements.txt
index 90f4339f..4cfa7bce 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -33,7 +33,7 @@ rlp<4,>=3
 semantic_version
 scikit-learn
 transaction>=2.2.1
-z3-solver<4.12.2.0,>=4.8.8.0
+z3-solver<=4.12.5.0,>=4.8.8.0
 matplotlib
 pre-commit<2.21.0
 certifi>=2020.06.20