diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index 5bc2c049114..e0bfab53e76 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1437,6 +1437,7 @@
         pattern_parentheses,
         pattern_type,
         pattern_types,
+        permissions_from_mode,
         phantom_data,
         pic,
         pie,
diff --git a/library/std/src/os/unix/fs.rs b/library/std/src/os/unix/fs.rs
index caf6980afd9..a964db2e0ac 100644
--- a/library/std/src/os/unix/fs.rs
+++ b/library/std/src/os/unix/fs.rs
@@ -334,6 +334,7 @@ pub trait PermissionsExt {
     /// assert_eq!(permissions.mode(), 0o644);
     /// ```
     #[stable(feature = "fs_ext", since = "1.1.0")]
+    #[cfg_attr(not(test), rustc_diagnostic_item = "permissions_from_mode")]
     fn from_mode(mode: u32) -> Self;
 }
 
diff --git a/src/tools/clippy/clippy_lints/src/non_octal_unix_permissions.rs b/src/tools/clippy/clippy_lints/src/non_octal_unix_permissions.rs
index b915df52762..cfc15d92715 100644
--- a/src/tools/clippy/clippy_lints/src/non_octal_unix_permissions.rs
+++ b/src/tools/clippy/clippy_lints/src/non_octal_unix_permissions.rs
@@ -1,6 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::{snippet_with_applicability, SpanRangeExt};
-use clippy_utils::{match_def_path, paths};
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
@@ -63,7 +62,7 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
             ExprKind::Call(func, [param]) => {
                 if let ExprKind::Path(ref path) = func.kind
                     && let Some(def_id) = cx.qpath_res(path, func.hir_id).opt_def_id()
-                    && match_def_path(cx, def_id, &paths::PERMISSIONS_FROM_MODE)
+                    && cx.tcx.is_diagnostic_item(sym::permissions_from_mode, def_id)
                     && let ExprKind::Lit(_) = param.kind
                     && param.span.eq_ctxt(expr.span)
                     && param
diff --git a/src/tools/clippy/clippy_utils/src/paths.rs b/src/tools/clippy/clippy_utils/src/paths.rs
index dd304e7aae8..c7b1c01de1d 100644
--- a/src/tools/clippy/clippy_utils/src/paths.rs
+++ b/src/tools/clippy/clippy_utils/src/paths.rs
@@ -39,8 +39,6 @@
 pub const PARKING_LOT_MUTEX_GUARD: [&str; 3] = ["lock_api", "mutex", "MutexGuard"];
 pub const PARKING_LOT_RWLOCK_READ_GUARD: [&str; 3] = ["lock_api", "rwlock", "RwLockReadGuard"];
 pub const PARKING_LOT_RWLOCK_WRITE_GUARD: [&str; 3] = ["lock_api", "rwlock", "RwLockWriteGuard"];
-#[cfg_attr(not(unix), allow(clippy::invalid_paths))]
-pub const PERMISSIONS_FROM_MODE: [&str; 6] = ["std", "os", "unix", "fs", "PermissionsExt", "from_mode"];
 pub const REGEX_BUILDER_NEW: [&str; 3] = ["regex", "RegexBuilder", "new"];
 pub const REGEX_BYTES_BUILDER_NEW: [&str; 4] = ["regex", "bytes", "RegexBuilder", "new"];
 pub const REGEX_BYTES_NEW: [&str; 4] = ["regex", "bytes", "Regex", "new"];