diff --git a/llvm/utils/gn/secondary/libcxx/src/BUILD.gn b/llvm/utils/gn/secondary/libcxx/src/BUILD.gn
index cf73739b251e..bcaa28102608 100644
--- a/llvm/utils/gn/secondary/libcxx/src/BUILD.gn
+++ b/llvm/utils/gn/secondary/libcxx/src/BUILD.gn
@@ -184,6 +184,7 @@ if (libcxx_enable_filesystem) {
     "filesystem/directory_iterator.cpp",
     "filesystem/filesystem_common.h",
     "filesystem/operations.cpp",
+    "filesystem/posix_compat.h",
   ]
   if (libcxx_use_compiler_rt) {
     cxx_sources += [ "filesystem/int128_builtins.cpp" ]