diff --git a/setup.py b/setup.py
index 09d5def43..acdf46c5c 100644
--- a/setup.py
+++ b/setup.py
@@ -29,7 +29,7 @@
         "cadquery-ocp>=7.7.0a0,<7.8",
         "ezdxf",
         "multimethod>=1.11,<2.0",
-        "nlopt",
+        "nlopt>=2.9.0,<3.0",
         "typish",
         "casadi",
         "path",