diff --git a/src/libstore/gc.cc b/src/libstore/gc.cc
index f8c4a0723..8e90913cc 100644
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -379,7 +379,7 @@ void LocalStore::findRuntimeRoots(PathSet & roots)
         auto digitsRegex = std::regex(R"(^\d+$)");
         auto mapRegex = std::regex(R"(^\s*\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+(/\S+)\s*$)");
         auto storePathRegex = std::regex(quoteRegexChars(storeDir) + R"(/[0-9a-z]+[0-9a-zA-Z\+\-\._\?=]*)");
-        while (errno = 0, ent = readdir(procDir)) {
+        while (errno = 0, ent = readdir(procDir.get())) {
             checkInterrupt();
             if (std::regex_match(ent->d_name, digitsRegex)) {
                 readProcLink((format("/proc/%1%/exe") % ent->d_name).str(), paths);
@@ -393,14 +393,14 @@ void LocalStore::findRuntimeRoots(PathSet & roots)
                     throw SysError(format("opening %1%") % fdStr);
                 }
                 struct dirent * fd_ent;
-                while (errno = 0, fd_ent = readdir(fdDir)) {
+                while (errno = 0, fd_ent = readdir(fdDir.get())) {
                     if (fd_ent->d_name[0] != '.') {
                         readProcLink((format("%1%/%2%") % fdStr % fd_ent->d_name).str(), paths);
                     }
                 }
                 if (errno)
                     throw SysError(format("iterating /proc/%1%/fd") % ent->d_name);
-                fdDir.close();
+                fdDir.reset();
 
                 auto mapLines =
                     tokenizeString<std::vector<string>>(readFile((format("/proc/%1%/maps") % ent->d_name).str(), true), "\n");
@@ -651,13 +651,13 @@ void LocalStore::tryToDelete(GCState & state, const Path & path)
    the link count. */
 void LocalStore::removeUnusedLinks(const GCState & state)
 {
-    AutoCloseDir dir = opendir(linksDir.c_str());
+    AutoCloseDir dir(opendir(linksDir.c_str()));
     if (!dir) throw SysError(format("opening directory ‘%1%’") % linksDir);
 
     long long actualSize = 0, unsharedSize = 0;
 
     struct dirent * dirent;
-    while (errno = 0, dirent = readdir(dir)) {
+    while (errno = 0, dirent = readdir(dir.get())) {
         checkInterrupt();
         string name = dirent->d_name;
         if (name == "." || name == "..") continue;
@@ -776,7 +776,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
 
         try {
 
-            AutoCloseDir dir = opendir(realStoreDir.c_str());
+            AutoCloseDir dir(opendir(realStoreDir.c_str()));
             if (!dir) throw SysError(format("opening directory ‘%1%’") % realStoreDir);
 
             /* Read the store and immediately delete all paths that
@@ -787,7 +787,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                can start faster. */
             Paths entries;
             struct dirent * dirent;
-            while (errno = 0, dirent = readdir(dir)) {
+            while (errno = 0, dirent = readdir(dir.get())) {
                 checkInterrupt();
                 string name = dirent->d_name;
                 if (name == "." || name == "..") continue;
@@ -798,7 +798,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                     tryToDelete(state, path);
             }
 
-            dir.close();
+            dir.reset();
 
             /* Now delete the unreachable valid paths.  Randomise the
                order in which we delete entries to make the collector
diff --git a/src/libstore/optimise-store.cc b/src/libstore/optimise-store.cc
index 454c8b49d..b71c7e905 100644
--- a/src/libstore/optimise-store.cc
+++ b/src/libstore/optimise-store.cc
@@ -47,11 +47,11 @@ LocalStore::InodeHash LocalStore::loadInodeHash()
     debug("loading hash inodes in memory");
     InodeHash inodeHash;
 
-    AutoCloseDir dir = opendir(linksDir.c_str());
+    AutoCloseDir dir(opendir(linksDir.c_str()));
     if (!dir) throw SysError(format("opening directory ‘%1%’") % linksDir);
 
     struct dirent * dirent;
-    while (errno = 0, dirent = readdir(dir)) { /* sic */
+    while (errno = 0, dirent = readdir(dir.get())) { /* sic */
         checkInterrupt();
         // We don't care if we hit non-hash files, anything goes
         inodeHash.insert(dirent->d_ino);
@@ -68,11 +68,11 @@ Strings LocalStore::readDirectoryIgnoringInodes(const Path & path, const InodeHa
 {
     Strings names;
 
-    AutoCloseDir dir = opendir(path.c_str());
+    AutoCloseDir dir(opendir(path.c_str()));
     if (!dir) throw SysError(format("opening directory ‘%1%’") % path);
 
     struct dirent * dirent;
-    while (errno = 0, dirent = readdir(dir)) { /* sic */
+    while (errno = 0, dirent = readdir(dir.get())) { /* sic */
         checkInterrupt();
 
         if (inodeHash.count(dirent->d_ino)) {
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index 0e1849df0..961c14e3a 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -234,11 +234,11 @@ DirEntries readDirectory(const Path & path)
     DirEntries entries;
     entries.reserve(64);
 
-    AutoCloseDir dir = opendir(path.c_str());
+    AutoCloseDir dir(opendir(path.c_str()));
     if (!dir) throw SysError(format("opening directory ‘%1%’") % path);
 
     struct dirent * dirent;
-    while (errno = 0, dirent = readdir(dir)) { /* sic */
+    while (errno = 0, dirent = readdir(dir.get())) { /* sic */
         checkInterrupt();
         string name = dirent->d_name;
         if (name == "." || name == "..") continue;
@@ -642,48 +642,6 @@ void Pipe::create()
 
 
 
-//////////////////////////////////////////////////////////////////////
-
-
-AutoCloseDir::AutoCloseDir()
-{
-    dir = 0;
-}
-
-
-AutoCloseDir::AutoCloseDir(DIR * dir)
-{
-    this->dir = dir;
-}
-
-
-AutoCloseDir::~AutoCloseDir()
-{
-    close();
-}
-
-
-void AutoCloseDir::operator =(DIR * dir)
-{
-    this->dir = dir;
-}
-
-
-AutoCloseDir::operator DIR *()
-{
-    return dir;
-}
-
-
-void AutoCloseDir::close()
-{
-    if (dir) {
-        closedir(dir);
-        dir = 0;
-    }
-}
-
-
 //////////////////////////////////////////////////////////////////////
 
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index d42099781..679c3a1b6 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -180,18 +180,15 @@ public:
 };
 
 
-class AutoCloseDir
+struct DIRDeleter
 {
-    DIR * dir;
-public:
-    AutoCloseDir();
-    AutoCloseDir(DIR * dir);
-    ~AutoCloseDir();
-    void operator =(DIR * dir);
-    operator DIR *();
-    void close();
+    void operator()(DIR * dir) const {
+        closedir(dir);
+    }
 };
 
+typedef std::unique_ptr<DIR, DIRDeleter> AutoCloseDir;
+
 
 class Pid
 {