diff --git a/pyproject.toml b/pyproject.toml
index d99804b..8604bf2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,7 +20,7 @@ classifiers = [
 ]
 dependencies = [
     "ipython==8.20",
-    "multimethod==1.12",
+    "multimethod>=1.12,<1.13",
     "numpy==2.0",
     "sympy==1.13.3",
     "tabulate==0.9",