diff --git a/components/script/dom/bindings/iterable.rs b/components/script/dom/bindings/iterable.rs
index 0228e31caae1..15fbe7175cb2 100644
--- a/components/script/dom/bindings/iterable.rs
+++ b/components/script/dom/bindings/iterable.rs
@@ -105,8 +105,7 @@ impl<T: DomObject + JSTraceable + Iterable> IterableIterator<T> {
         };
         self.index.set(index + 1);
         result.map(|_| {
-            assert!(!rval.is_null());
-            unsafe { NonNull::new_unchecked(rval.get()) }
+            NonNull::new(rval.get()).expect("got a null pointer")
         })
     }
 }
diff --git a/components/script/dom/imagedata.rs b/components/script/dom/imagedata.rs
index 9a51c0088d18..9e80d86d0892 100644
--- a/components/script/dom/imagedata.rs
+++ b/components/script/dom/imagedata.rs
@@ -160,7 +160,6 @@ impl ImageDataMethods for ImageData {
     #[allow(unsafe_code)]
     // https://html.spec.whatwg.org/multipage/#dom-imagedata-data
     unsafe fn Data(&self, _: *mut JSContext) -> NonNull<JSObject> {
-        assert!(!self.data.get().is_null());
-        NonNull::new_unchecked(self.data.get())
+        NonNull::new(self.data.get()).expect("got a null pointer")
     }
 }
diff --git a/components/script/dom/testbinding.rs b/components/script/dom/testbinding.rs
index aeaad77eb116..2dd774275909 100644
--- a/components/script/dom/testbinding.rs
+++ b/components/script/dom/testbinding.rs
@@ -154,8 +154,7 @@ impl TestBindingMethods for TestBinding {
     #[allow(unsafe_code)]
     unsafe fn ArrayAttribute(&self, cx: *mut JSContext) -> NonNull<JSObject> {
         rooted!(in(cx) let array = JS_NewUint8ClampedArray(cx, 16));
-        assert!(!array.is_null());
-        NonNull::new_unchecked(array.get())
+        NonNull::new(array.get()).expect("got a null pointer")
     }
     #[allow(unsafe_code)]
     unsafe fn AnyAttribute(&self, _: *mut JSContext) -> JSVal { NullValue() }
@@ -164,8 +163,7 @@ impl TestBindingMethods for TestBinding {
     #[allow(unsafe_code)]
     unsafe fn ObjectAttribute(&self, cx: *mut JSContext) -> NonNull<JSObject> {
         rooted!(in(cx) let obj = JS_NewPlainObject(cx));
-        assert!(!obj.is_null());
-        NonNull::new_unchecked(obj.get())
+        NonNull::new(obj.get()).expect("got a null pointer")
     }
     #[allow(unsafe_code)]
     unsafe fn SetObjectAttribute(&self, _: *mut JSContext, _: *mut JSObject) {}
diff --git a/components/script/dom/xmlhttprequest.rs b/components/script/dom/xmlhttprequest.rs
index eb4804b20531..cb42db58ad40 100644
--- a/components/script/dom/xmlhttprequest.rs
+++ b/components/script/dom/xmlhttprequest.rs
@@ -1123,8 +1123,8 @@ impl XMLHttpRequest {
     unsafe fn arraybuffer_response(&self, cx: *mut JSContext) -> Option<NonNull<JSObject>> {
         // Step 1
         let created = self.response_arraybuffer.get();
-        if !created.is_null() {
-            return Some(NonNull::new_unchecked(created));
+        if let Some(nonnull) = NonNull::new(created) {
+            return Some(nonnull)
         }
 
         // Step 2