diff --git a/alloc/Cargo.toml b/alloc/Cargo.toml
index 024b92790e970..612452a960a37 100644
--- a/alloc/Cargo.toml
+++ b/alloc/Cargo.toml
@@ -47,8 +47,6 @@ optimize_for_size = ["core/optimize_for_size"]
 
 [lints.rust.unexpected_cfgs]
 level = "warn"
-# x.py uses beta cargo, so `check-cfg` entries do not yet take effect
-# for rust-lang/rust. But for users of `-Zbuild-std` it does.
 check-cfg = [
     'cfg(bootstrap)',
     'cfg(no_global_oom_handling)',
diff --git a/core/Cargo.toml b/core/Cargo.toml
index cf9fddd269aa4..cace4582b489a 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -39,8 +39,6 @@ debug_refcell = []
 
 [lints.rust.unexpected_cfgs]
 level = "warn"
-# x.py uses beta cargo, so `check-cfg` entries do not yet take effect
-# for rust-lang/rust. But for users of `-Zbuild-std` it does.
 check-cfg = [
     'cfg(bootstrap)',
     'cfg(no_fp_fmt_parse)',
diff --git a/std/Cargo.toml b/std/Cargo.toml
index 32479cd2836fa..358510b8f77d8 100644
--- a/std/Cargo.toml
+++ b/std/Cargo.toml
@@ -100,8 +100,6 @@ test = true
 
 [lints.rust.unexpected_cfgs]
 level = "warn"
-# x.py uses beta cargo, so `check-cfg` entries do not yet take effect
-# for rust-lang/rust. But for users of `-Zbuild-std` it does.
 check-cfg = [
     'cfg(bootstrap)',
     'cfg(target_arch, values("xtensa"))',