diff --git a/si-units/src/extra_units.rs b/si-units/src/extra_units.rs
index dc4fcfd..6259427 100644
--- a/si-units/src/extra_units.rs
+++ b/si-units/src/extra_units.rs
@@ -1,8 +1,8 @@
-use crate::{PySIObject, QuantityError, _JOULE, _KELVIN, _METER};
+use crate::{_JOULE, _KELVIN, _METER, PySIObject, QuantityError};
+use pyo3::PyTypeInfo;
 use pyo3::exceptions::PyTypeError;
 use pyo3::prelude::*;
 use pyo3::types::{PyFloat, PyNotImplemented};
-use pyo3::PyTypeInfo;
 
 #[pyclass(module = "si_units")]
 #[derive(Clone, Copy)]
@@ -110,6 +110,10 @@ impl Angle {
         Self(-self.0)
     }
 
+    fn value_in(&self, unit: Self) -> f64 {
+        self.0 / unit.0
+    }
+
     fn sin(&self) -> f64 {
         self.0.sin()
     }
diff --git a/si-units/src/lib.rs b/si-units/src/lib.rs
index dc36a43..73e1f07 100644
--- a/si-units/src/lib.rs
+++ b/si-units/src/lib.rs
@@ -135,11 +135,17 @@ impl PySIObject {
         self.unit.eq(&other.unit)
     }
 
-    pub fn value_in<'py>(&self, py: Python<'py>, unit: &Self) -> PyResult<Bound<'py, PyAny>> {
-        self.check_units(unit)?;
-        self.value
-            .bind(py)
-            .call_method1("__truediv__", (&unit.value,))
+    pub fn value_in<'py>(
+        &self,
+        py: Python<'py>,
+        unit: &Bound<'py, PyAny>,
+    ) -> PyResult<Bound<'py, PyAny>> {
+        if unit.cast::<Celsius>().is_ok() {
+            return self.__truediv__(unit);
+        }
+        let u = unit.extract::<PyRef<Self>>()?;
+        self.check_units(&u)?;
+        self.value.bind(py).call_method1("__truediv__", (&u.value,))
     }
 
     #[classattr]
diff --git a/si-units/src/si_units/_core.pyi b/si-units/src/si_units/_core.pyi
index e3b956b..576fd61 100644
--- a/si-units/src/si_units/_core.pyi
+++ b/si-units/src/si_units/_core.pyi
@@ -204,6 +204,7 @@ class Angle:
     def __rmul__(self, lhs: float) -> Self: ...
     def __truediv__(self, rhs: Any) -> Any: ...
     def __neg__(self) -> Self: ...
+    def value_in(self, unit: Self) -> float: ...
     def sin(self) -> float: ...
     def cos(self) -> float: ...
     def tan(self) -> float: ...