diff --git a/core/src/avm1/script_object.rs b/core/src/avm1/script_object.rs
index 4cccd34bd..f0f83e918 100644
--- a/core/src/avm1/script_object.rs
+++ b/core/src/avm1/script_object.rs
@@ -760,9 +760,11 @@ mod tests {
                 player: None,
                 load_manager: &mut LoadManager::new(),
                 system: &mut SystemProperties::default(),
+                instance_counter: &mut 0,
             };
 
             root.post_instantiation(&mut avm, &mut context, root, None, false);
+            root.set_name(context.gc_context, "");
 
             let object = ScriptObject::object(gc_context, Some(avm.prototypes().object)).into();
 
diff --git a/core/src/avm1/test_utils.rs b/core/src/avm1/test_utils.rs
index fef6644cf..5a2cf16a8 100644
--- a/core/src/avm1/test_utils.rs
+++ b/core/src/avm1/test_utils.rs
@@ -59,8 +59,10 @@ where
             player: None,
             load_manager: &mut LoadManager::new(),
             system: &mut SystemProperties::default(),
+            instance_counter: &mut 0,
         };
         root.post_instantiation(&mut avm, &mut context, root, None, false);
+        root.set_name(context.gc_context, "");
 
         let globals = avm.global_object_cell();
         avm.insert_stack_frame(GcCell::allocate(
diff --git a/core/src/context.rs b/core/src/context.rs
index 2893c93cc..acc483cd6 100644
--- a/core/src/context.rs
+++ b/core/src/context.rs
@@ -100,6 +100,9 @@ pub struct UpdateContext<'a, 'gc, 'gc_context> {
 
     /// The system properties
     pub system: &'a mut SystemProperties,
+
+    /// The current instance ID. Used to generate default `instanceN` names.
+    pub instance_counter: &'a mut i32,
 }
 
 /// A queued ActionScript call.
diff --git a/core/src/display_object.rs b/core/src/display_object.rs
index 234f48152..1998f2633 100644
--- a/core/src/display_object.rs
+++ b/core/src/display_object.rs
@@ -889,6 +889,15 @@ pub trait TDisplayObject<'gc>: 'gc + Collect + Debug + Into<DisplayObject<'gc>>
             })
             .expect("All objects must have root")
     }
+
+    /// Assigns a default instance name `instanceN` to this object.
+    fn set_default_instance_name(&mut self, context: &mut UpdateContext<'_, 'gc, '_>) {
+        if self.name().is_empty() {
+            let name = format!("instance{}", *context.instance_counter);
+            self.set_name(context.gc_context, &name);
+            *context.instance_counter = context.instance_counter.wrapping_add(1);
+        }
+    }
 }
 
 pub enum DisplayObjectPtr {}
diff --git a/core/src/display_object/button.rs b/core/src/display_object/button.rs
index a19462525..4199705f6 100644
--- a/core/src/display_object/button.rs
+++ b/core/src/display_object/button.rs
@@ -124,6 +124,8 @@ impl<'gc> TDisplayObject<'gc> for Button<'gc> {
         _init_object: Option<Object<'gc>>,
         _instantiated_from_avm: bool,
     ) {
+        self.set_default_instance_name(context);
+
         let mut mc = self.0.write(context.gc_context);
         if mc.object.is_none() {
             let object = StageObject::for_display_object(
diff --git a/core/src/display_object/edit_text.rs b/core/src/display_object/edit_text.rs
index e35dc017e..00e0e3231 100644
--- a/core/src/display_object/edit_text.rs
+++ b/core/src/display_object/edit_text.rs
@@ -435,6 +435,8 @@ impl<'gc> TDisplayObject<'gc> for EditText<'gc> {
         _init_object: Option<Object<'gc>>,
         _instantiated_from_avm: bool,
     ) {
+        self.set_default_instance_name(context);
+
         let mut text = self.0.write(context.gc_context);
         if text.object.is_none() {
             let object = StageObject::for_display_object(
diff --git a/core/src/display_object/movie_clip.rs b/core/src/display_object/movie_clip.rs
index 47a5f70dd..868e235a2 100644
--- a/core/src/display_object/movie_clip.rs
+++ b/core/src/display_object/movie_clip.rs
@@ -722,6 +722,8 @@ impl<'gc> TDisplayObject<'gc> for MovieClip<'gc> {
         init_object: Option<Object<'gc>>,
         instantiated_from_avm: bool,
     ) {
+        self.set_default_instance_name(context);
+
         if self.0.read().object.is_none() {
             // If we are running within the AVM, this must be an immediate action.
             // If we are not, then this must be queued to be ran first-thing
diff --git a/core/src/player.rs b/core/src/player.rs
index 4a63690a7..7562ea406 100644
--- a/core/src/player.rs
+++ b/core/src/player.rs
@@ -139,6 +139,9 @@ pub struct Player {
 
     system: SystemProperties,
 
+    /// The current instance ID. Used to generate default `instanceN` names.
+    instance_counter: i32,
+
     /// Self-reference to ourselves.
     ///
     /// This is a weak reference that is upgraded and handed out in various
@@ -238,6 +241,7 @@ impl Player {
             input,
             self_reference: None,
             system: SystemProperties::default(),
+            instance_counter: 0,
         };
 
         player.mutate_with_update_context(|avm, context| {
@@ -245,6 +249,7 @@ impl Player {
                 MovieClip::from_movie(context.gc_context, movie.clone()).into();
             root.set_depth(context.gc_context, 0);
             root.post_instantiation(avm, context, root, None, false);
+            root.set_name(context.gc_context, "");
             context.levels.insert(0, root);
 
             if let Ok(object) = root.object().as_object() {
@@ -846,6 +851,7 @@ impl Player {
             stage_height,
             player,
             system_properties,
+            instance_counter,
         ) = (
             self.player_version,
             self.global_time,
@@ -861,6 +867,7 @@ impl Player {
             Twips::from_pixels(self.movie_height.into()),
             self.self_reference.clone(),
             &mut self.system,
+            &mut self.instance_counter,
         );
 
         self.gc_arena.mutate(|gc_context, gc_root| {
@@ -891,6 +898,7 @@ impl Player {
                 player,
                 load_manager,
                 system: system_properties,
+                instance_counter,
             };
 
             let ret = f(avm, &mut update_context);