diff --git a/rithm/_hints.py b/rithm/_hints.py
index 10a6607..f5170ef 100644
--- a/rithm/_hints.py
+++ b/rithm/_hints.py
@@ -1,7 +1,11 @@
 from __future__ import annotations
 
 from numbers import Rational as _Rational
-from typing import TYPE_CHECKING, overload as _overload
+from typing import (
+    SupportsIndex as _SupportsIndex,
+    TYPE_CHECKING,
+    overload as _overload,
+)
 
 from typing_extensions import Any as _Any, Self as _Self, final as _final
 
@@ -130,7 +134,7 @@ def numerator(self, /) -> _Self: ...
 
         def bit_length(self, /) -> _Self: ...
 
-        def gcd(self, other: _Self, /) -> _Self: ...
+        def gcd(self, other: _SupportsIndex, /) -> _Self: ...
 
         def is_power_of_two(self, /) -> bool: ...
 
diff --git a/rithm/_rithm.py b/rithm/_rithm.py
index 542061a..f90159c 100644
--- a/rithm/_rithm.py
+++ b/rithm/_rithm.py
@@ -4,7 +4,7 @@
 from numbers import Integral, Rational
 from operator import mul
 from sys import hash_info
-from typing import Any, NoReturn, overload
+from typing import Any, NoReturn, SupportsIndex, overload
 
 from typing_extensions import Self, final
 
@@ -25,8 +25,8 @@ def numerator(self, /) -> Self:
     def bit_length(self, /) -> Self:
         return Int(self._value.bit_length())
 
-    def gcd(self, other: Self, /) -> Self:
-        return Int(_gcd(self._value, other._value))
+    def gcd(self, other: SupportsIndex, /) -> Self:
+        return Int(_gcd(self._value, other))
 
     def is_power_of_two(self, /) -> bool:
         return self._value > 0 and not (self._value & (self._value - 1))
diff --git a/src/python_binding/py_int.rs b/src/python_binding/py_int.rs
index 49060bd..0587d02 100644
--- a/src/python_binding/py_int.rs
+++ b/src/python_binding/py_int.rs
@@ -129,8 +129,8 @@ impl PyInt {
     }
 
     #[pyo3(text_signature = "($self, other, /)")]
-    fn gcd(&self, other: &Self) -> PyInt {
-        Self((&self.0).gcd(&other.0))
+    fn gcd(&self, other: &Bound<'_, PyAny>) -> PyResult<PyInt> {
+        Ok(Self((&self.0).gcd(&try_big_int_from_py_integral(other)?)))
     }
 
     #[pyo3(signature = (endianness, /))]