diff --git a/components/style/gecko/snapshot_helpers.rs b/components/style/gecko/snapshot_helpers.rs
index 3cb325bb6b1..d75cd275310 100644
--- a/components/style/gecko/snapshot_helpers.rs
+++ b/components/style/gecko/snapshot_helpers.rs
@@ -44,14 +44,14 @@ unsafe fn get_class_or_part_from_attr(attr: &structs::nsAttrValue) -> Class {
             structs::nsAttrValue_ValueType_eAtomArray
         );
         // NOTE: Bindgen doesn't deal with AutoTArray, so cast it below.
-        let array: *mut u8 = *(*container)
+        let attr_array: *mut _ = *(*container)
             .__bindgen_anon_1
             .mValue
             .as_ref()
             .__bindgen_anon_1
             .mAtomArray
             .as_ref();
-        let array = array as *const structs::nsTArray<structs::RefPtr<nsAtom>>;
+        let array = (*attr_array).mArray.as_ptr() as *const structs::nsTArray<structs::RefPtr<nsAtom>>;
         return Class::More(&**array);
     }
     debug_assert_eq!(base_type, structs::nsAttrValue_ValueBaseType_eStringBase);