diff --git a/src/display/display_utils.js b/src/display/display_utils.js
index 711ecae6c..f3d152326 100644
--- a/src/display/display_utils.js
+++ b/src/display/display_utils.js
@@ -794,13 +794,10 @@ class CSSConstants {
   }
 }
 
-function applyOpacity(r, g, b, opacity) {
+function applyOpacity(color, opacity) {
   opacity = MathClamp(opacity ?? 1, 0, 1);
   const white = 255 * (1 - opacity);
-  r = Math.round(r * opacity + white);
-  g = Math.round(g * opacity + white);
-  b = Math.round(b * opacity + white);
-  return [r, g, b];
+  return color.map(c => Math.round(c * opacity + white));
 }
 
 function RGBToHSL(rgb, output) {
diff --git a/test/unit/display_utils_spec.js b/test/unit/display_utils_spec.js
index 87da7c0ca..28be4d441 100644
--- a/test/unit/display_utils_spec.js
+++ b/test/unit/display_utils_spec.js
@@ -323,7 +323,7 @@ describe("display_utils", function () {
       ctx.globalAlpha = 0.8;
       ctx.fillRect(0, 0, 1, 1);
       const [r, g, b] = ctx.getImageData(0, 0, 1, 1).data;
-      expect(applyOpacity(123, 45, 67, ctx.globalAlpha)).toEqual([r, g, b]);
+      expect(applyOpacity([123, 45, 67], ctx.globalAlpha)).toEqual([r, g, b]);
     });
   });
 
diff --git a/web/comment_manager.js b/web/comment_manager.js
index 394a01ee4..9625c9fb9 100644
--- a/web/comment_manager.js
+++ b/web/comment_manager.js
@@ -132,7 +132,7 @@ class CommentManager {
     return this.#hasForcedColors
       ? null
       : findContrastColor(
-          applyOpacity(...color, opacity ?? 1),
+          applyOpacity(color, opacity ?? 1),
           CSSConstants.commentForegroundColor
         );
   }