diff --git a/servo/components/style/gecko/snapshot.rs b/servo/components/style/gecko/snapshot.rs
index d294939baeb8..cffb78d3e9e0 100644
--- a/servo/components/style/gecko/snapshot.rs
+++ b/servo/components/style/gecko/snapshot.rs
@@ -211,7 +211,7 @@ impl ElementSnapshot for GeckoElementSnapshot {
             return;
         }
 
-        snapshot_helpers::each_class(&self.mClass, callback)
+        snapshot_helpers::each_class_or_part(&self.mClass, callback)
     }
 
     #[inline]
diff --git a/servo/components/style/gecko/snapshot_helpers.rs b/servo/components/style/gecko/snapshot_helpers.rs
index aaa2254dbd76..b8b31bc87dd3 100644
--- a/servo/components/style/gecko/snapshot_helpers.rs
+++ b/servo/components/style/gecko/snapshot_helpers.rs
@@ -107,9 +107,9 @@ pub fn has_class_or_part(
 }
 
 /// Given an item, a callback, and a getter, execute `callback` for each class
-/// this `item` has.
+/// or part name this `item` has.
 #[inline(always)]
-pub fn each_class<F>(attr: &structs::nsAttrValue, mut callback: F)
+pub fn each_class_or_part<F>(attr: &structs::nsAttrValue, mut callback: F)
 where
     F: FnMut(&Atom),
 {
diff --git a/servo/components/style/gecko/wrapper.rs b/servo/components/style/gecko/wrapper.rs
index 17c1cfaf35db..ba2951f6f25b 100644
--- a/servo/components/style/gecko/wrapper.rs
+++ b/servo/components/style/gecko/wrapper.rs
@@ -1372,7 +1372,19 @@ impl<'le> TElement for GeckoElement<'le> {
             None => return,
         };
 
-        snapshot_helpers::each_class(attr, callback)
+        snapshot_helpers::each_class_or_part(attr, callback)
+    }
+
+    fn each_part<F>(&self, callback: F)
+    where
+        F: FnMut(&Atom),
+    {
+        let attr = match self.get_part_attr() {
+            Some(c) => c,
+            None => return,
+        };
+
+        snapshot_helpers::each_class_or_part(attr, callback)
     }
 
     #[inline]