diff --git a/setup.py b/setup.py
index 9820854ea..a4f4671d8 100644
--- a/setup.py
+++ b/setup.py
@@ -93,7 +93,7 @@ def run(self) -> None:
         "pydotplus >=2, <3",
         "pygls >=1.1, <2",
         "ruamel.yaml >=0.17, <0.18",
-        "z3-solver >=4, <5",
+        "z3-solver >=4, <4.12.3",
     ],
     extras_require={
         "devel": [