--- a/servo/components/style/gecko_bindings/bindings.rs
+++ b/servo/components/style/gecko_bindings/bindings.rs
@@ -619,16 +619,21 @@ extern "C" {
 }
 extern "C" {
     pub fn Gecko_EnsureImageLayersLength(layers: *mut nsStyleImageLayers,
                                          len: usize,
                                          layer_type:
                                              nsStyleImageLayers_LayerType);
 }
 extern "C" {
+    pub fn Gecko_EnsureStyleAnimationArrayLength(array:
+                                                     *mut ::std::os::raw::c_void,
+                                                 len: usize);
+}
+extern "C" {
     pub fn Gecko_ResetStyleCoord(unit: *mut nsStyleUnit,
                                  value: *mut nsStyleUnion);
 }
 extern "C" {
     pub fn Gecko_SetStyleCoordCalcValue(unit: *mut nsStyleUnit,
                                         value: *mut nsStyleUnion,
                                         calc: nsStyleCoord_CalcValue);
 }