diff --git a/benches/microbenchmarks.rs b/benches/microbenchmarks.rs
index 1c3bfea55a3..7909c8e445e 100644
--- a/benches/microbenchmarks.rs
+++ b/benches/microbenchmarks.rs
@@ -107,6 +107,9 @@ fn bench_rustpython_code(group: &mut BenchmarkGroup<'_, WallTime>, bench: &Micro
     settings.path_list.push("Lib/".to_string());
     settings.write_bytecode = false;
     settings.user_site_directory = false;
+    // Pin the str/bytes hash secret so dict/set probe sequences (and thus
+    // timings) are reproducible across benchmark runs.
+    settings.hash_seed = Some(0);
 
     let builder = Interpreter::builder(settings);
     let defs = rustpython_stdlib::stdlib_module_defs(&builder.ctx);