diff --git a/subprojects/packagefiles/equivalent-1-rs/meson.build b/subprojects/packagefiles/equivalent-1-rs/meson.build
index c57c23ea96d..6309928ad2e 100644
--- a/subprojects/packagefiles/equivalent-1-rs/meson.build
+++ b/subprojects/packagefiles/equivalent-1-rs/meson.build
@@ -8,7 +8,7 @@ project(
 lib = static_library(
   'equivalent',
   'src/lib.rs',
-  override_options : ['rust_std=2021', 'build.rust_std=2021'],
+  override_options : ['rust_std=2015', 'build.rust_std=2015'],
   rust_abi : 'rust',
   native : true,
 )