diff --git a/servo/components/script/dom/canvasgradient.rs b/servo/components/script/dom/canvasgradient.rs
index 8d65753b5d6cd..0a011b0db2bff 100644
--- a/servo/components/script/dom/canvasgradient.rs
+++ b/servo/components/script/dom/canvasgradient.rs
@@ -366,7 +366,7 @@ offset
 :
 Finite
 <
-f32
+f64
 >
 color
 :
diff --git a/servo/components/script/dom/webidls/CanvasGradient.webidl b/servo/components/script/dom/webidls/CanvasGradient.webidl
index da8c5588d7950..defe8a8f74881 100644
--- a/servo/components/script/dom/webidls/CanvasGradient.webidl
+++ b/servo/components/script/dom/webidls/CanvasGradient.webidl
@@ -91,6 +91,32 @@ MPL
 .
 *
 /
+/
+/
+https
+:
+/
+/
+html
+.
+spec
+.
+whatwg
+.
+org
+/
+#
+canvasgradient
+/
+/
+[
+Exposed
+=
+(
+Window
+Worker
+)
+]
 interface
 CanvasGradient
 {
@@ -98,17 +124,10 @@ CanvasGradient
 /
 opaque
 object
-/
-/
-addColorStop
-should
-take
-a
-double
 void
 addColorStop
 (
-float
+double
 offset
 DOMString
 color