diff --git a/.gitmodules b/.gitmodules
index 00dadd8..d3fc285 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -14,3 +14,6 @@
 [submodule "extras/spiffs/spiffs"]
 	path = extras/spiffs/spiffs
 	url = https://github.com/pellepl/spiffs.git
+[submodule "examples/posix_fs/fs-test"]
+	path = examples/posix_fs/fs-test
+	url = https://github.com/sheinz/fs-test
diff --git a/core/newlib_syscalls.c b/core/newlib_syscalls.c
index 023872c..c8104a9 100644
--- a/core/newlib_syscalls.c
+++ b/core/newlib_syscalls.c
@@ -41,7 +41,7 @@ IRAM caddr_t _sbrk_r (struct _reent *r, int incr)
 }
 
 /* syscall implementation for stdio write to UART */
-long _write_r(struct _reent *r, int fd, const char *ptr, int len )
+__attribute__((weak)) long _write_r(struct _reent *r, int fd, const char *ptr, int len )
 {
     if(fd != r->_stdout->_file) {
         r->_errno = EBADF;
@@ -79,10 +79,20 @@ __attribute__((weak)) long _read_r( struct _reent *r, int fd, char *ptr, int len
 /* Stub syscall implementations follow, to allow compiling newlib functions that
    pull these in via various codepaths
 */
-__attribute__((alias("syscall_returns_enosys"))) int _open_r(struct _reent *r, const char *pathname, int flags, int mode);
-__attribute__((alias("syscall_returns_enosys"))) int _fstat_r(struct _reent *r, int fd, void *buf);
-__attribute__((alias("syscall_returns_enosys"))) int _close_r(struct _reent *r, int fd);
-__attribute__((alias("syscall_returns_enosys"))) off_t _lseek_r(struct _reent *r, int fd, off_t offset, int whence);
+__attribute__((weak, alias("syscall_returns_enosys"))) 
+int _open_r(struct _reent *r, const char *pathname, int flags, int mode);
+
+__attribute__((weak, alias("syscall_returns_enosys"))) 
+int _close_r(struct _reent *r, int fd);
+
+__attribute__((weak, alias("syscall_returns_enosys"))) 
+int _unlink_r(struct _reent *r, const char *path);
+
+__attribute__((alias("syscall_returns_enosys"))) 
+int _fstat_r(struct _reent *r, int fd, void *buf);
+
+__attribute__((alias("syscall_returns_enosys"))) 
+off_t _lseek_r(struct _reent *r, int fd, off_t offset, int whence);
 
 /* Generic stub for any newlib syscall that fails with errno ENOSYS
    ("Function not implemented") and a return value equivalent to
diff --git a/examples/posix_fs/Makefile b/examples/posix_fs/Makefile
new file mode 100644
index 0000000..bf45ed7
--- /dev/null
+++ b/examples/posix_fs/Makefile
@@ -0,0 +1,11 @@
+PROGRAM=posix_fs_example
+PROGRAM_EXTRA_SRC_FILES=./fs-test/fs_test.c
+
+EXTRA_COMPONENTS = extras/spiffs
+FLASH_SIZE = 32
+
+# spiffs configuration
+SPIFFS_BASE_ADDR = 0x200000
+SPIFFS_SIZE = 0x100000
+
+include ../../common.mk
diff --git a/examples/posix_fs/fs-test b/examples/posix_fs/fs-test
new file mode 160000
index 0000000..983ed83
--- /dev/null
+++ b/examples/posix_fs/fs-test
@@ -0,0 +1 @@
+Subproject commit 983ed830a8d2bd1a3eaa586ed608530f9d29201e
diff --git a/examples/posix_fs/posix_fs_example.c b/examples/posix_fs/posix_fs_example.c
new file mode 100644
index 0000000..7e3ad8f
--- /dev/null
+++ b/examples/posix_fs/posix_fs_example.c
@@ -0,0 +1,41 @@
+#include "espressif/esp_common.h"
+#include "esp/uart.h"
+#include "FreeRTOS.h"
+#include "task.h"
+#include "esp8266.h"
+#include <stdio.h>
+
+#include "esp_spiffs.h"
+#include "spiffs.h"
+
+#include "fs-test/fs_test.h"
+
+
+void test_task(void *pvParameters)
+{
+    esp_spiffs_mount();
+    esp_spiffs_unmount();  // FS must be unmounted before formating
+    if (SPIFFS_format(&fs) == SPIFFS_OK) {
+        printf("Format complete\n");
+    } else {
+        printf("Format failed\n");
+    }
+    esp_spiffs_mount();
+
+    while (1) {
+        vTaskDelay(5000 / portTICK_RATE_MS);
+
+        if (fs_test_run(10000)) {
+            printf("PASS\n");
+        } else {
+            printf("FAIL\n");
+        }
+    }
+}
+
+void user_init(void)
+{
+    uart_set_baud(0, 115200);
+
+    xTaskCreate(test_task, (signed char *)"test_task", 1024, NULL, 2, NULL);
+}
diff --git a/extras/spiffs/esp_spiffs.c b/extras/spiffs/esp_spiffs.c
index d6ec7d6..194d697 100644
--- a/extras/spiffs/esp_spiffs.c
+++ b/extras/spiffs/esp_spiffs.c
@@ -9,6 +9,7 @@
 #include "spiffs.h"
 #include <espressif/spi_flash.h>
 #include <stdbool.h>
+#include <esp/uart.h>
 
 spiffs fs;
 
@@ -185,3 +186,53 @@ void esp_spiffs_unmount()
     fds_buf = 0;
     cache_buf = 0;
 }
+
+/* syscall implementation for stdio write to UART */
+long _write_r(struct _reent *r, int fd, const char *ptr, int len )
+{
+    if(fd != r->_stdout->_file) {
+        return SPIFFS_write(&fs, (spiffs_file)fd, (char*)ptr, len);
+    }
+    for(int i = 0; i < len; i++) {
+        /* Auto convert CR to CRLF, ignore other LFs (compatible with Espressif SDK behaviour) */
+        if(ptr[i] == '\r')
+            continue;
+        if(ptr[i] == '\n')
+            uart_putc(0, '\r');
+        uart_putc(0, ptr[i]);
+    }
+    return len;
+}
+
+/* syscall implementation for stdio read from UART */
+long _read_r( struct _reent *r, int fd, char *ptr, int len )
+{
+    int ch, i;
+
+    if(fd != r->_stdin->_file) {
+        return SPIFFS_read(&fs, (spiffs_file)fd, ptr, len);
+    }
+    uart_rxfifo_wait(0, 1);
+    for(i = 0; i < len; i++) {
+        ch = uart_getc_nowait(0);
+        if (ch < 0) break;
+        ptr[i] = ch;
+    }
+    return i;
+}
+
+/* syscall implementation for stdio write to UART */
+int _open_r(struct _reent *r, const char *pathname, int flags, int mode)
+{
+    return SPIFFS_open(&fs, pathname, flags, mode);
+}
+
+int _close_r(struct _reent *r, int fd)
+{
+    return SPIFFS_close(&fs, (spiffs_file)fd);
+}
+
+int _unlink_r(struct _reent *r, const char *path)
+{
+    return SPIFFS_remove(&fs, path);
+}