--- a/servo/components/style/keyframes.rs
+++ b/servo/components/style/keyframes.rs
@@ -297,17 +297,17 @@ impl KeyframesAnimation {
 
         // Prepend autogenerated keyframes if appropriate.
         if steps[0].start_percentage.0 != 0. {
             steps.insert(0, KeyframesStep::new(KeyframePercentage::new(0.),
                                                KeyframesStepValue::ComputedValues));
         }
 
         if steps.last().unwrap().start_percentage.0 != 1. {
-            steps.push(KeyframesStep::new(KeyframePercentage::new(0.),
+            steps.push(KeyframesStep::new(KeyframePercentage::new(1.),
                                           KeyframesStepValue::ComputedValues));
         }
 
         Some(KeyframesAnimation {
             steps: steps,
             properties_changed: animated_properties,
         })
     }