diff --git a/src/wutil.cpp b/src/wutil.cpp
index b12c0c5c3..b9601ba06 100644
--- a/src/wutil.cpp
+++ b/src/wutil.cpp
@@ -26,6 +26,7 @@
 
 #include "common.h"
 #include "fallback.h"  // IWYU pragma: keep
+#include "fds.h"
 #include "flog.h"
 #include "wcstringutil.h"
 
@@ -764,6 +765,10 @@ file_id_t file_id_for_fd(int fd) {
     return result;
 }
 
+file_id_t file_id_for_fd(const autoclose_fd_t &fd) {
+    return file_id_for_fd(fd.fd());
+}
+
 file_id_t file_id_for_path(const wcstring &path) {
     file_id_t result = kInvalidFileID;
     struct stat buf = {};
@@ -786,6 +791,20 @@ bool file_id_t::operator==(const file_id_t &rhs) const { return this->compare_fi
 
 bool file_id_t::operator!=(const file_id_t &rhs) const { return !(*this == rhs); }
 
+
+wcstring file_id_t::dump() const {
+    using llong = long long;
+    wcstring result;
+    append_format(result, L"     device: %lld\n", llong(device));
+    append_format(result, L"      inode: %lld\n", llong(inode));
+    append_format(result, L"       size: %lld\n", llong(size));
+    append_format(result, L"     change: %lld\n", llong(change_seconds));
+    append_format(result, L"change_nano: %lld\n", llong(change_nanoseconds));
+    append_format(result, L"        mod: %lld\n", llong(mod_seconds));
+    append_format(result, L"   mod_nano: %lld", llong(mod_nanoseconds));
+    return result;
+}
+
 template <typename T>
 int compare(T a, T b) {
     if (a < b) {
diff --git a/src/wutil.h b/src/wutil.h
index 8fecde585..6698b29f9 100644
--- a/src/wutil.h
+++ b/src/wutil.h
@@ -19,6 +19,8 @@
 #include "common.h"
 #include "maybe.h"
 
+class autoclose_fd_t;
+
 /// Wide character version of opendir(). Note that opendir() is guaranteed to set close-on-exec by
 /// POSIX (hooray).
 DIR *wopendir(const wcstring &name);
@@ -155,6 +157,8 @@ struct file_id_t {
 
     static file_id_t from_stat(const struct stat &buf);
 
+    wcstring dump() const;
+
    private:
     int compare_file_id(const file_id_t &rhs) const;
 };
@@ -184,6 +188,7 @@ struct hash<file_id_t> {
 #endif
 
 file_id_t file_id_for_fd(int fd);
+file_id_t file_id_for_fd(const autoclose_fd_t &fd);
 file_id_t file_id_for_path(const wcstring &path);
 file_id_t file_id_for_path(const std::string &path);