diff --git a/src/browser/webapi/IdleDeadline.zig b/src/browser/webapi/IdleDeadline.zig
index c871702e..b193f561 100644
--- a/src/browser/webapi/IdleDeadline.zig
+++ b/src/browser/webapi/IdleDeadline.zig
@@ -20,6 +20,9 @@ const std = @import("std");
 
 const IdleDeadline = @This();
 
+// Padding to avoid zero-size struct, which causes identity_map pointer collisions.
+_pad: bool = false,
+
 pub fn init() IdleDeadline {
     return .{};
 }