diff --git a/CHANGELOG.md b/CHANGELOG.md
index eff0e72..12fc10e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,10 @@ You can find its changes [documented below](#032-2025-09-10).
 
 This release has an [MSRV][] of 1.82.
 
+### Added
+
+* Add `lerp_rect_unpremultiplied` to interpolate `AlphaColor` without premultiplying alpha (in unpremultiplied "straight" alpha space). ([#199][] by [@tomcur][])
+
 ## [0.3.2][] (2025-09-10)
 
 This release has an [MSRV][] of 1.82.
@@ -209,6 +213,7 @@ This is the initial release.
 [#175]: https://github.com/linebender/color/pull/175
 [#185]: https://github.com/linebender/color/pull/185
 [#190]: https://github.com/linebender/color/pull/190
+[#199]: https://github.com/linebender/color/pull/199
 
 [Unreleased]: https://github.com/linebender/color/compare/v0.3.2...HEAD
 [0.3.2]: https://github.com/linebender/color/releases/tag/v0.3.2
diff --git a/color/src/color.rs b/color/src/color.rs
index be5a07a..2d0bfba 100644
--- a/color/src/color.rs
+++ b/color/src/color.rs
@@ -475,6 +475,16 @@ impl<CS: ColorSpace> AlphaColor<CS> {
             .un_premultiply()
     }
 
+    /// Interpolate colors without premultiplying alpha (in unpremultiplied "straight" alpha space).
+    ///
+    /// Note: this function doesn't fix up hue in cylindrical spaces. It is
+    /// still useful if the hue angles are compatible, particularly if the
+    /// fixup has been applied.
+    #[must_use]
+    pub fn lerp_rect_unpremultiplied(self, other: Self, t: f32) -> Self {
+        self + t * (other - self)
+    }
+
     /// Linearly interpolate colors, with hue fixup if needed.
     #[must_use]
     pub fn lerp(self, other: Self, t: f32, direction: HueDirection) -> Self {