diff --git a/src/main.zig b/src/main.zig
index cc3d468..e41d25f 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -181,6 +181,10 @@ fn runRelay() !void {
     // GPA logs every allocation that was never freed, with stack traces.
     var gpa: std.heap.DebugAllocator(.{
         .stack_trace_frames = if (build_options.use_gpa) 8 else 0,
+        // catch use-after-free at the use site with the free site's stack:
+        // freed regions are kept unmapped-but-tracked instead of recycled.
+        .retain_metadata = build_options.use_gpa,
+        .never_unmap = build_options.use_gpa,
     }) = .init;
     defer if (build_options.use_gpa) {
         log.info("GPA: checking for leaks...", .{});