diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index ed7eb4b..285ee1e 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -26,6 +26,10 @@ repos:
     additional_dependencies:
     - flake8-bugbear
     - flake8-comprehensions
+- repo: https://github.com/pre-commit/mirrors-mypy
+  rev: "v1.9.0"
+  hooks:
+  - id: mypy
 - repo: https://github.com/mgedmin/check-manifest
   rev: "0.49"
   hooks:
diff --git a/rules/predicates.py b/rules/predicates.py
index 72821d3..08d9689 100644
--- a/rules/predicates.py
+++ b/rules/predicates.py
@@ -64,13 +64,13 @@ def __init__(
         assert callable(fn), "The given predicate is not callable."
         innerfn = fn
         if isinstance(fn, Predicate):
-            fn, num_args, var_args, name = (
+            innerfn, num_args, var_args, name = (
                 fn.fn,
                 fn.num_args,
                 fn.var_args,
                 name or fn.name,
             )
-            innerfn = fn
+            fn = innerfn
         elif isinstance(fn, partial):
             innerfn = fn.func
             argspec = getfullargspec(innerfn)