Index: configure.ac
==================================================================
--- configure.ac
+++ configure.ac
@@ -495,17 +495,11 @@
 	AC_MSG_RESULT($ac_cv_snprintf_useful_ret)
 ])
 test x"$have_asprintf" != x"yes" -a x"$ac_cv_snprintf_useful_ret" != x"yes" && \
 	AC_MSG_ERROR(No asprintf and no snprintf returning required space!)
 
-AC_CHECK_FUNC(arc4random, [
-	AC_DEFINE(HAVE_ARC4RANDOM, 1, [Whether we have arc4random()])
-], [
-	AC_CHECK_FUNC(random, [
-		AC_DEFINE(HAVE_RANDOM, 1, [Whether we have random()])
-	])
-])
+AC_CHECK_FUNCS([arc4random random], break)
 
 AC_CHECK_LIB(dl, dlopen, LIBS="$LIBS -ldl")
 AC_CHECK_HEADERS(dlfcn.h)
 case "$host_os" in
 	netbsd*)
@@ -693,10 +687,12 @@
 	AS_HELP_STRING([--disable-files], [disable file support]))
 AS_IF([test x"$enable_files" != x"no"], [
 	AC_DEFINE(OF_HAVE_FILES, 1, [Whether we have files])
 	AC_SUBST(USE_SRCS_FILES, '${SRCS_FILES}')
 	AC_SUBST(OFZIP, "ofzip$ac_cv_exeext")
+
+	AC_CHECK_FUNCS(readdir_r)
 ])
 
 AC_CHECK_FUNCS([sysconf gmtime_r localtime_r nanosleep lstat])
 
 AC_CHECK_HEADERS([pwd.h grp.h])

Index: src/OFFile.m
==================================================================
--- src/OFFile.m
+++ src/OFFile.m
@@ -114,10 +114,13 @@
 #define DIR_MODE DEFAULT_MODE | S_IXUSR | S_IXGRP | S_IXOTH
 
 #if defined(OF_HAVE_CHOWN) && defined(OF_HAVE_THREADS)
 static of_mutex_t mutex;
 #endif
+#if !defined(HAVE_READDIR_R) && !defined(_WIN32) && defined(OF_HAVE_THREADS)
+static of_mutex_t mutex;
+#endif
 
 int
 of_stat(OFString *path, of_stat_t *buffer)
 {
 #ifdef _WIN32
@@ -185,10 +188,16 @@
 	if (self != [OFFile class])
 		return;
 
 #if defined(OF_HAVE_CHOWN) && defined(OF_HAVE_THREADS)
 	if (!of_mutex_new(&mutex))
+		@throw [OFInitializationFailedException
+		    exceptionWithClass: self];
+#endif
+
+#if !defined(HAVE_READDIR_R) && !defined(_WIN32) && defined(OF_HAVE_THREADS)
+	if (!of_mutex_new(&mutex))
 		@throw [OFInitializationFailedException
 		    exceptionWithClass: self];
 #endif
 
 #ifdef __wii__
@@ -360,35 +369,61 @@
 
 	files = [OFMutableArray array];
 
 #ifndef _WIN32
 	DIR *dir;
-	struct dirent *dirent;
 
 	encoding = [OFString nativeOSEncoding];
 
 	if ((dir = opendir([path cStringWithEncoding: encoding])) == NULL)
 		@throw [OFOpenFileFailedException exceptionWithPath: path
 							       mode: @"r"];
 
+# if !defined(HAVE_READDIR_R) && defined(OF_HAVE_THREADS)
+	if (!of_mutex_lock(&mutex))
+		@throw [OFLockFailedException exception];
+# endif
+
 	@try {
-		while ((dirent = readdir(dir)) != NULL) {
-			void *pool = objc_autoreleasePoolPush();
+		for (;;) {
+			struct dirent *dirent;
+# ifdef HAVE_READDIR_R
+			struct dirent buffer;
+# endif
+			void *pool;
 			OFString *file;
+
+# ifdef HAVE_READDIR_R
+			if (readdir_r(dir, &buffer, &dirent) != 0)
+				@throw [OFReadFailedException
+				    exceptionWithObject: self
+					requestedLength: 0];
+# else
+			dirent = readdir(dir);
+# endif
+
+			if (dirent == NULL)
+				break;
 
 			if (strcmp(dirent->d_name, ".") == 0 ||
 			    strcmp(dirent->d_name, "..") == 0)
 				continue;
+
+			pool = objc_autoreleasePoolPush();
 
 			file = [OFString stringWithCString: dirent->d_name
 						  encoding: encoding];
 			[files addObject: file];
 
 			objc_autoreleasePoolPop(pool);
 		}
 	} @finally {
 		closedir(dir);
+# if !defined(HAVE_READDIR_R) && defined(OF_HAVE_THREADS)
+		if (!of_mutex_unlock(&mutex))
+			@throw [OFUnlockFailedException exception];
+# endif
 	}
 #else
 	void *pool = objc_autoreleasePoolPush();
 	HANDLE handle;
 	WIN32_FIND_DATAW fd;