diff --git a/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc b/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc
index 5daa7eb8ded..aff0c372789 100644
--- a/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc
+++ b/gcc/rust/checks/errors/borrowck/rust-borrow-checker.cc
@@ -28,13 +28,7 @@ void
 mkdir_wrapped (const std::string &dirname)
 {
   int ret;
-#ifdef _WIN32
-  ret = _mkdir (dirname.c_str ());
-#elif unix
   ret = mkdir (dirname.c_str (), 0775);
-#elif __APPLE__
-  ret = mkdir (dirname.c_str (), 0775);
-#endif
   (void) ret;
 }
 
diff --git a/gcc/rust/expand/rust-proc-macro.cc b/gcc/rust/expand/rust-proc-macro.cc
index 09680733e98..3518bffaf03 100644
--- a/gcc/rust/expand/rust-proc-macro.cc
+++ b/gcc/rust/expand/rust-proc-macro.cc
@@ -102,6 +102,7 @@ static_assert (
 
 } // namespace
 
+#ifndef _WIN32
 template <typename Symbol, typename Callback>
 bool
 register_callback (void *handle, Symbol, std::string symbol_name,
@@ -125,6 +126,7 @@ register_callback (void *handle, Symbol, std::string symbol_name,
 
 #define REGISTER_CALLBACK(HANDLE, SYMBOL, CALLBACK)                            \
   register_callback (HANDLE, SYMBOL, #SYMBOL, CALLBACK)
+#endif  // _WIN32
 
 const ProcMacro::ProcmacroArray *
 load_macros_array (std::string path)
diff --git a/gcc/rust/parse/rust-parse.cc b/gcc/rust/parse/rust-parse.cc
index 504a409cc4d..b78ac524f61 100644
--- a/gcc/rust/parse/rust-parse.cc
+++ b/gcc/rust/parse/rust-parse.cc
@@ -89,7 +89,7 @@ extract_module_path (const AST::AttrVec &inner_attrs,
   // Source: rustc compiler
   // (https://github.com/rust-lang/rust/blob/9863bf51a52b8e61bcad312f81b5193d53099f9f/compiler/rustc_expand/src/module.rs#L174)
 #if defined(HAVE_DOS_BASED_FILE_SYSTEM)
-  path.replace ('/', '\\');
+  std::replace(path.begin(), path.end(), '/', '\\');
 #endif /* HAVE_DOS_BASED_FILE_SYSTEM */
 
   return path;