diff --git a/src/components/script/dom/bindings/codegen/CodegenRust.py b/src/components/script/dom/bindings/codegen/CodegenRust.py
index 70fa8e6515c..af9a39313da 100644
--- a/src/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/src/components/script/dom/bindings/codegen/CodegenRust.py
@@ -1274,6 +1274,10 @@ for (uint32_t i = 0; i < length; ++i) {
         else:
             assert(tag == IDLType.Tags.bool)
             defaultStr = toStringBool(defaultValue.value)
+
+        if type.nullable():
+            defaultStr = "Some(%s)" % defaultStr
+
         template = CGWrapper(CGIndenter(CGGeneric(template)),
                              pre="if ${haveValue} {\n",
                              post=("\n"
diff --git a/src/components/script/dom/testbinding.rs b/src/components/script/dom/testbinding.rs
index 35dc025cdae..1df1f97e606 100644
--- a/src/components/script/dom/testbinding.rs
+++ b/src/components/script/dom/testbinding.rs
@@ -123,15 +123,15 @@ impl TestBinding {
     // pub fn PassOptionalNullableStringWithDefault(&self, _: Option<DOMString>) {}
     pub fn PassOptionalNullableInterfaceWithDefault(&self, _: Option<JS<Blob>>) {}
 
-    // pub fn PassOptionalNullableBooleanWithNonNullDefault(&self, _: Option<bool>) {}
-    // pub fn PassOptionalNullableByteWithNonNullDefault(&self, _: Option<i8>) {}
-    // pub fn PassOptionalNullableOctetWithNonNullDefault(&self, _: Option<u8>) {}
-    // pub fn PassOptionalNullableShortWithNonNullDefault(&self, _: Option<i16>) {}
-    // pub fn PassOptionalNullableUnsignedShortWithNonNullDefault(&self, _: Option<u16>) {}
-    // pub fn PassOptionalNullableLongWithNonNullDefault(&self, _: Option<i32>) {}
-    // pub fn PassOptionalNullableUnsignedLongWithNonNullDefault(&self, _: Option<u32>) {}
-    // pub fn PassOptionalNullableLongLongWithNonNullDefault(&self, _: Option<i64>) {}
-    // pub fn PassOptionalNullableUnsignedLongLongWithNonNullDefault(&self, _: Option<u64>) {}
+    pub fn PassOptionalNullableBooleanWithNonNullDefault(&self, _: Option<bool>) {}
+    pub fn PassOptionalNullableByteWithNonNullDefault(&self, _: Option<i8>) {}
+    pub fn PassOptionalNullableOctetWithNonNullDefault(&self, _: Option<u8>) {}
+    pub fn PassOptionalNullableShortWithNonNullDefault(&self, _: Option<i16>) {}
+    pub fn PassOptionalNullableUnsignedShortWithNonNullDefault(&self, _: Option<u16>) {}
+    pub fn PassOptionalNullableLongWithNonNullDefault(&self, _: Option<i32>) {}
+    pub fn PassOptionalNullableUnsignedLongWithNonNullDefault(&self, _: Option<u32>) {}
+    pub fn PassOptionalNullableLongLongWithNonNullDefault(&self, _: Option<i64>) {}
+    pub fn PassOptionalNullableUnsignedLongLongWithNonNullDefault(&self, _: Option<u64>) {}
     // pub fn PassOptionalNullableFloatWithNonNullDefault(&self, _: Option<f32>) {}
     // pub fn PassOptionalNullableDoubleWithNonNullDefault(&self, _: Option<f64>) {}
     // pub fn PassOptionalNullableStringWithNonNullDefault(&self, _: Option<DOMString>) {}
diff --git a/src/components/script/dom/webidls/TestBinding.webidl b/src/components/script/dom/webidls/TestBinding.webidl
index c9d1a6745c4..5c0420d5160 100644
--- a/src/components/script/dom/webidls/TestBinding.webidl
+++ b/src/components/script/dom/webidls/TestBinding.webidl
@@ -83,15 +83,15 @@ interface TestBinding {
   // void passOptionalNullableStringWithDefault(optional DOMString? arg = null);
   void passOptionalNullableInterfaceWithDefault(optional Blob? arg = null);
 
-  // void passOptionalNullableBooleanWithNonNullDefault(optional boolean? arg = false);
-  // void passOptionalNullableByteWithNonNullDefault(optional byte? arg = 7);
-  // void passOptionalNullableOctetWithNonNullDefault(optional octet? arg = 7);
-  // void passOptionalNullableShortWithNonNullDefault(optional short? arg = 7);
-  // void passOptionalNullableUnsignedShortWithNonNullDefault(optional unsigned short? arg = 7);
-  // void passOptionalNullableLongWithNonNullDefault(optional long? arg = 7);
-  // void passOptionalNullableUnsignedLongWithNonNullDefault(optional unsigned long? arg = 7);
-  // void passOptionalNullableLongLongWithNonNullDefault(optional long long? arg = 7);
-  // void passOptionalNullableUnsignedLongLongWithNonNullDefault(optional unsigned long long? arg = 7);
+  void passOptionalNullableBooleanWithNonNullDefault(optional boolean? arg = false);
+  void passOptionalNullableByteWithNonNullDefault(optional byte? arg = 7);
+  void passOptionalNullableOctetWithNonNullDefault(optional octet? arg = 7);
+  void passOptionalNullableShortWithNonNullDefault(optional short? arg = 7);
+  void passOptionalNullableUnsignedShortWithNonNullDefault(optional unsigned short? arg = 7);
+  void passOptionalNullableLongWithNonNullDefault(optional long? arg = 7);
+  void passOptionalNullableUnsignedLongWithNonNullDefault(optional unsigned long? arg = 7);
+  void passOptionalNullableLongLongWithNonNullDefault(optional long long? arg = 7);
+  void passOptionalNullableUnsignedLongLongWithNonNullDefault(optional unsigned long long? arg = 7);
   // void passOptionalNullableFloatWithNonNullDefault(optional float? arg = 0.0);
   // void passOptionalNullableDoubleWithNonNullDefault(optional double? arg = 0.0);
   // void passOptionalNullableStringWithNonNullDefault(optional DOMString? arg = "");