diff --git a/crates/oxide_vm/src/mem.rs b/crates/oxide_vm/src/mem.rs
index 9d97a003..7b6333a6 100644
--- a/crates/oxide_vm/src/mem.rs
+++ b/crates/oxide_vm/src/mem.rs
@@ -90,6 +90,10 @@ impl Epoch {
         self.bump.alloc(value)
     }
 
+    pub fn bump(&self) -> &bumpalo::Bump {
+        &self.bump
+    }
+
     /// Bump-allocate a value using a closure for initialization.
     /// Better for compiler optimization — construct directly on arena.
     pub fn alloc_with<T, F>(&self, f: F) -> *mut T
diff --git a/crates/oxide_vm/src/object.rs b/crates/oxide_vm/src/object.rs
index 53b33274..cf4b8a6f 100644
--- a/crates/oxide_vm/src/object.rs
+++ b/crates/oxide_vm/src/object.rs
@@ -138,6 +138,13 @@ impl JsObject {
         }
     }
 
+    pub fn set_prop_expand(&mut self, offset: u8, val: JsValue, bump: &bumpalo::Bump) {
+        if offset >= 4 && (self.overflow.is_null() || offset >= self.prop_count()) {
+            self.alloc_overflow(bump, (offset as usize) + 1);
+        }
+        self.set_prop(offset, val);
+    }
+
     pub fn proto(&self) -> JsValue {
         self.proto
     }
diff --git a/crates/oxide_vm/src/vm.rs b/crates/oxide_vm/src/vm.rs
index f1a91d3e..b3bfba57 100644
--- a/crates/oxide_vm/src/vm.rs
+++ b/crates/oxide_vm/src/vm.rs
@@ -76,6 +76,13 @@ impl Vm {
         None
     }
 
+    pub fn rerun(&mut self) -> Result<JsValue, String> {
+        self.pc = 0;
+        self.regs = [JsValue::undefined(); 256];
+        self.frames.clear();
+        self.dispatch()
+    }
+
     pub fn run(&mut self, module: &CompiledModule) -> Result<JsValue, String> {
         self.string_table.clear();
         self.string_reverse.clear();
@@ -349,7 +356,7 @@ impl Vm {
                         let new_shape_id = shape::make_shape(obj.shape_id(), prop_name_si);
                         obj.set_shape_id(new_shape_id);
                         obj.set_prop_count(new_offset + 1);
-                        obj.set_prop(new_offset, self.regs[a]);
+                        obj.set_prop_expand(new_offset, self.regs[a], &self.epoch.bump());
                         obj.bump_generation();
                     }
                 }
@@ -388,7 +395,7 @@ impl Vm {
                         let new_shape_id = shape::make_shape(obj.shape_id(), prop_name_si);
                         obj.set_shape_id(new_shape_id);
                         obj.set_prop_count(new_offset + 1);
-                        obj.set_prop(new_offset, self.regs[b]);
+                        obj.set_prop_expand(new_offset, self.regs[b], &self.epoch.bump());
                         obj.bump_generation();
                     }
                 }