diff --git a/rust-once_cell.spec b/rust-once_cell.spec
index e10f5f0..060f469 100644
--- a/rust-once_cell.spec
+++ b/rust-once_cell.spec
@@ -1,5 +1,7 @@
 # Generated by rust2rpm 23
-%bcond_without check
+# * tests only compile with Rust 1.63+:
+#   https://github.com/matklad/once_cell/issues/211
+%bcond_with check
 %global debug_package %{nil}
 
 %global crate once_cell