diff --git a/src/browser/js/ExecutionWorld.zig b/src/browser/js/ExecutionWorld.zig
index 2c381b9a..b4a45f78 100644
--- a/src/browser/js/ExecutionWorld.zig
+++ b/src/browser/js/ExecutionWorld.zig
@@ -88,7 +88,7 @@ pub fn createContext(self: *ExecutionWorld, page: *Page, enter: bool) !*Context
         global_template.setNamedProperty(v8.NamedPropertyHandlerConfiguration{
             .getter = unknownPropertyCallback,
             .flags = v8.PropertyHandlerFlags.NonMasking | v8.PropertyHandlerFlags.OnlyInterceptStrings,
-        }, v8.External.init(isolate, page));
+        }, null);
 
         const context_local = v8.Context.init(isolate, global_template, null);
         const v8_context = v8.Persistent(v8.Context).init(isolate, context_local).castToContext();
@@ -157,10 +157,6 @@ pub fn resumeExecution(self: *const ExecutionWorld) void {
 pub fn unknownPropertyCallback(c_name: ?*const v8.C_Name, raw_info: ?*const v8.C_PropertyCallbackInfo) callconv(.c) u8 {
     const info = v8.PropertyCallbackInfo.initFromV8(raw_info);
 
-    const data_value = info.getData();
-    const external = data_value.castTo(v8.External);
-    const page: *Page = @ptrCast(@alignCast(external.get()));
-
     const context = Context.fromIsolate(info.getIsolate());
     const maybe_property: ?[]u8 = context.valueToString(.{ .handle = c_name.? }, .{}) catch null;
 
@@ -188,7 +184,7 @@ pub fn unknownPropertyCallback(c_name: ?*const v8.C_Name, raw_info: ?*const v8.C
 
     if (maybe_property) |prop| {
         if (!ignored.has(prop)) {
-            const document = page.document;
+            const document = context.page.document;
 
             if (document.getElementById(prop)) |el| {
                 const js_value = context.zigValueToJs(el, .{}) catch {
diff --git a/src/browser/js/Function.zig b/src/browser/js/Function.zig
index 47ddbdb1..7e88b926 100644
--- a/src/browser/js/Function.zig
+++ b/src/browser/js/Function.zig
@@ -115,8 +115,19 @@ pub fn tryCallWithThis(self: *const Function, comptime T: type, this: anytype, a
 
 pub fn callWithThis(self: *const Function, comptime T: type, this: anytype, args: anytype) !T {
     const context = self.context;
-    context.call_depth += 1;
-    defer context.call_depth -= 1;
+
+    // When we're calling a function from within JavaScript itself, this isn't
+    // necessary. We're within a Caller instantiation, which will already have
+    // incremented the call_depth and it won't decrement it until the Caller is
+    // done.
+    // But some JS functions are initiated from Zig code, and not v8. For
+    // example, Observers, some event and window callbacks. In those cases, we
+    // need to increase the call_depth so that the call_arena remains valid for
+    // the duration of the function call. If we don't do this, the call_arena
+    // will be reset after each statement of the function which executes Zig code.
+    const call_depth = context.call_depth;
+    context.call_depth = call_depth + 1;
+    defer context.call_depth = call_depth;
 
     const js_this = try context.valueToExistingObject(this);