build/contrib/detpax/INSTALL |  2 ++
 build/contrib/detpax/main.c  | 59 +++++++++++++++++++++++++++++++++++++++++++++--------

diff --git a/build/contrib/detpax/INSTALL b/build/contrib/detpax/INSTALL
index c4c3f6b293210f0e26f198b58802e2d4190a875727f8c548bd732130f73181ea..ac8d1791145430adbe1f45749b212db8f01ea01f324376655f8954cddf9ee9d5 100644
--- a/build/contrib/detpax/INSTALL
+++ b/build/contrib/detpax/INSTALL
@@ -4,3 +4,5 @@ For glibc maybe you will need:
     $ CFLAGS=-D_DEFAULT_SOURCE ./build
 For debug build:
     $ STRIP=: CFLAGS="-g -O0 -Weverything" ./build
+
+Add -DWITH_GETDENTS to use non-POSIX more efficient getdents().
diff --git a/build/contrib/detpax/main.c b/build/contrib/detpax/main.c
index e68701063fdc4436ba3b64c5874d9de6c7194773423e80539571007fbb2b4611..4bfa7792c5af92bcef449b2e7c53366070a6da7c9d93d3ed1fd0475e6c80a4de 100644
--- a/build/contrib/detpax/main.c
+++ b/build/contrib/detpax/main.c
@@ -47,6 +47,18 @@ static size_t LinksLen = 0;    // hardlinks count
 static size_t DirsLen = 0;     // directories count
 static size_t SymlinksLen = 0; // symlinks count
 
+static bool
+isDots(const char *fn, const size_t fnLen)
+{
+    if ((fnLen == 2) && (fn[0] == '.') && (fn[1] == '.')) {
+        return true;
+    }
+    if ((fnLen == 1) && (fn[0] == '.')) {
+        return true;
+    }
+    return false;
+}
+
 static void
 walk(const struct Path *dir)
 {
@@ -54,15 +66,48 @@     Scratch[ScratchLen - 1] = 0;
     size_t curLen = PathMarshal((char *)Scratch, ScratchLen - 1, dir);
     char *cur = (char *)Scratch + ScratchLen - 1 - curLen;
     {
+        char *fn = NULL;
+        size_t fnLen = 0;
+        struct Str *strp = NULL;
+        struct dirent *e = NULL;
+#ifdef WITH_GETDENTS
+        int d = open(cur, O_RDONLY | O_DIRECTORY);
+        if (d == -1) {
+            err2("open(dir)", cur);
+        }
+        ssize_t n = -1;
+        ssize_t off = 0;
+        for (;;) {
+            n = getdents(d, (char *)Scratch, ScratchLen);
+            if (n <= 0) {
+                if (n < 0) {
+                    PathMarshal((char *)Scratch, ScratchLen - 1, dir);
+                    err2("getdents", cur);
+                }
+                break;
+            }
+            off = 0;
+            while (off < n) {
+                e = (void *)&(Scratch[off]);
+                off += e->d_reclen;
+                fn = e->d_name;
+                fnLen = e->d_namlen;
+                if (isDots(fn, fnLen)) {
+                    continue;
+                }
+                strp = KEKSMemPoolGet(&DirEnts);
+                memEnough("dirEnt", strp != NULL);
+                *strp = StrNewVal(fn, fnLen);
+            }
+        }
+        close(d);
+#else  // WITH_GETDENTS
         DIR *d = opendir(cur);
         if (d == NULL) {
             err2("opendir", cur);
         }
-        struct dirent *e = NULL;
-        char *fn = NULL;
-        size_t fnLen = 0;
-        struct Str *strp = NULL;
         for (;;) {
+            errno = 0;
             e = readdir(d);
             if (e == NULL) {
                 if (errno != 0) {
@@ -72,10 +117,7 @@                 break;
             }
             fn = e->d_name;
             fnLen = strlen(fn);
-            if ((fnLen == 2) && (fn[0] == '.') && (fn[1] == '.')) {
-                continue;
-            }
-            if ((fnLen == 1) && (fn[0] == '.')) {
+            if (isDots(fn, fnLen)) {
                 continue;
             }
             strp = KEKSMemPoolGet(&DirEnts);
@@ -83,6 +125,7 @@             memEnough("dirEnt", strp != NULL);
             *strp = StrNewVal(fn, fnLen);
         }
         closedir(d);
+#endif // WITH_GETDENTS
     }
     const size_t pathsLen = DirEnts.len;
     struct Str *paths = calloc(pathsLen, sizeof(struct Str));