diff --git a/src/lib-fs/Makefile.am b/src/lib-fs/Makefile.am
index 08bae08a66..e53bba5365 100644
--- a/src/lib-fs/Makefile.am
+++ b/src/lib-fs/Makefile.am
@@ -43,7 +43,8 @@ pkginc_lib_HEADERS = $(headers)
 noinst_PROGRAMS = $(test_programs)
 
 test_programs = \
-	test-fs-metawrap
+	test-fs-metawrap \
+	test-fs-posix
 
 test_deps = \
 	$(noinst_LTLIBRARIES) \
@@ -59,6 +60,10 @@ test_fs_metawrap_SOURCES = test-fs-metawrap.c
 test_fs_metawrap_LDADD = $(test_libs)
 test_fs_metawrap_DEPENDENCIES = $(test_deps)
 
+test_fs_posix_SOURCES = test-fs-posix.c
+test_fs_posix_LDADD = $(test_libs)
+test_fs_posix_DEPENDENCIES = $(test_deps)
+
 check: check-am check-test
 check-test: all-am
 	for bin in $(test_programs); do \
diff --git a/src/lib-fs/test-fs-posix.c b/src/lib-fs/test-fs-posix.c
new file mode 100644
index 0000000000..c9c1ef9408
--- /dev/null
+++ b/src/lib-fs/test-fs-posix.c
@@ -0,0 +1,115 @@
+/* Copyright (c) 2016-2017 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "str.h"
+#include "fs-api.h"
+#include "safe-mkdir.h"
+#include "safe-mkstemp.h"
+#include "test-common.h"
+#include "unlink-directory.h"
+#include <sys/stat.h>
+#include <unistd.h>
+
+static void test_fs_posix(void)
+{
+	const char testdir[] = ".test-fs-posix";
+	const char *unlink_err;
+
+	if (unlink_directory(testdir, UNLINK_DIRECTORY_FLAG_RMDIR, &unlink_err) < 0 &&
+	    errno != ENOENT) {
+		i_error("Couldn't prepare test directory (%s): %s", testdir, unlink_err);
+		goto error_no_testdir;
+	}
+	if (safe_mkdir(testdir, 0700, (uid_t)-1, (gid_t)-1) != 1) {
+		/* Something just raced us to create this directory, bail. */
+		goto error_no_testdir;
+	}
+
+	int ret;
+	const char *error;
+	struct fs *fs;
+	struct fs_settings fs_set;
+
+	test_begin("test-fs-posix filesystem");
+	i_zero(&fs_set);
+	ret = fs_init("posix", t_strdup_printf("prefix=%s/", testdir), &fs_set, &fs, &error);
+	test_out_quiet("fs_init() failed", ret >= 0);
+	if (ret < 0) {
+		test_end();
+		goto error_no_fs;
+	}
+
+	struct fs *ref = fs;
+	fs_ref(ref);
+	fs_unref(&ref);
+	test_assert(ref == NULL);
+	test_assert(fs != NULL);
+
+	test_assert(fs_get_parent(fs) == NULL);
+	test_assert_strcmp(fs_get_driver(fs), "posix");
+	test_end();
+
+	struct fs_file *file;
+	char buf[10];
+	ssize_t count;
+	test_begin("test-fs-posix bad file read");
+	file = fs_file_init(fs, "fail_1", FS_OPEN_MODE_READONLY);
+	test_assert(fs_exists(file) == 0);
+	count = fs_read(file, buf, 1);
+	test_assert(count == -1 && errno == ENOENT);
+	fs_file_deinit(&file);
+	test_end();
+
+	test_begin("test-fs-posix good file write");
+	file = fs_file_init(fs, "good1", FS_OPEN_MODE_REPLACE);
+	test_assert(file != NULL);
+	test_assert(fs_exists(file) == 0); /* file not created until data is written */
+	test_assert(fs_write(file, "X", 1) == 0);
+	test_assert(fs_exists(file) == 1);
+	fs_file_deinit(&file);
+	test_end();
+
+	test_begin("test-fs-posix good file read");
+	file = fs_file_init(fs, "good1", FS_OPEN_MODE_READONLY);
+	test_assert(fs_exists(file) == 1);
+	errno = 0;
+	count = fs_read(file, buf, 2);
+	test_assert(count == 1 && errno == 0);
+	fs_file_deinit(&file);
+	test_end();
+
+	struct fs_iter *iter = fs_iter_init(fs, "/", 0);
+	const char *filename;
+	test_begin("test-fs-posix iterator");
+	filename = fs_iter_next(iter);
+	test_assert_strcmp(filename, "good1");
+	test_assert(fs_iter_next(iter) == NULL);
+	fs_iter_deinit(&iter);
+	test_end();
+
+	struct stat st;
+	test_begin("test-fs-posix file stat and delete");
+	file = fs_file_init(fs, "good1", FS_OPEN_MODE_READONLY);
+	test_assert(fs_stat(file, &st) == 0);
+	test_assert(st.st_size == 1);
+	test_assert(fs_delete(file) == 0);
+	fs_file_deinit(&file);
+	test_end();
+
+	fs_deinit(&fs);
+
+error_no_fs:
+	if (unlink_directory(testdir, UNLINK_DIRECTORY_FLAG_RMDIR, &unlink_err) != 0)
+		i_error("Couldn't clean up test directory (%s): %s", testdir, unlink_err);
+error_no_testdir:
+	return;
+}
+
+int main(void)
+{
+	static void (*const test_functions[])(void) = {
+		test_fs_posix,
+		NULL
+	};
+	return test_run(test_functions);
+}