diff --git a/components/style/properties/helpers/animated_properties.mako.rs b/components/style/properties/helpers/animated_properties.mako.rs
index 0fffb440d01..85f8ec9281f 100644
--- a/components/style/properties/helpers/animated_properties.mako.rs
+++ b/components/style/properties/helpers/animated_properties.mako.rs
@@ -1185,12 +1185,12 @@ impl Animatable for LengthOrPercentageOrAuto {
             (this, other) => {
                 let this: Option<CalcLengthOrPercentage> = From::from(this);
                 let other: Option<CalcLengthOrPercentage> = From::from(other);
-                if this.is_none() || other.is_none() {
-                    Err(())
-                } else {
-                    let length_diff = (this.unwrap().length().0 - other.unwrap().length().0) as f64;
-                    let percentage_diff = (this.unwrap().percentage() - other.unwrap().percentage()) as f64;
+                if let (Some(this), Some(other)) = (this, other) {
+                    let length_diff = (this.length().0 - other.length().0) as f64;
+                    let percentage_diff = (this.percentage() - other.percentage()) as f64;
                     Ok(length_diff * length_diff + percentage_diff * percentage_diff)
+                } else {
+                    Err(())
                 }
             }
         }