diff --git a/CHANGELOG.md b/CHANGELOG.md
index bfc7b11eb..21bcac47b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # NHS.UK frontend Changelog
 
+## Unreleased
+
+- Fix Sass deprecation on `mix` function (passing a number without unit) ([PR 995](https://github.com/nhsuk/nhsuk-frontend/pull/995))
+
 ## 8.3.0 - 24 July 2024
 
 :new: **New features**
diff --git a/packages/core/settings/_colours.scss b/packages/core/settings/_colours.scss
index ab7a70892..b5b4ed63b 100644
--- a/packages/core/settings/_colours.scss
+++ b/packages/core/settings/_colours.scss
@@ -65,11 +65,11 @@ $alpha-transparency-50: 0.5;
 //
 
 @function tint($color, $percentage) {
-  @return mix(white, $color, $percentage * 1%);
+  @return mix(white, $color, $percentage);
 }
 
 @function shade($color, $percentage) {
-  @return mix(black, $color, $percentage * 1%);
+  @return mix(black, $color, $percentage);
 }
 
 //