diff --git a/os/os/__init__.py b/os/os/__init__.py
index 9b4c0f40..2e574f76 100644
--- a/os/os/__init__.py
+++ b/os/os/__init__.py
@@ -12,12 +12,18 @@ readdir_ = libc.func("P", "readdir", "P")
 read_ = libc.func("i", "read", "ipi")
 write_ = libc.func("i", "write", "iPi")
 close_ = libc.func("i", "close", "i")
+access_ = libc.func("i", "access", "si")
 fork_ = libc.func("i", "fork", "")
 pipe_ = libc.func("i", "pipe", "p")
 _exit_ = libc.func("v", "_exit", "i")
 getpid_ = libc.func("i", "getpid", "")
 waitpid_ = libc.func("i", "waitpid", "ipi")
 
+R_OK = const(4)
+W_OK = const(2)
+X_OK = const(1)
+F_OK = const(0)
+
 
 def check_error(ret):
     if ret == -1:
@@ -61,6 +67,8 @@ def close(fd):
     check_error(r)
     return r
 
+def access(path, mode):
+    return access_(path, mode) == 0
 
 def fork():
     r = fork_()
diff --git a/os/test_filestat.py b/os/test_filestat.py
new file mode 100644
index 00000000..91014a92
--- /dev/null
+++ b/os/test_filestat.py
@@ -0,0 +1,5 @@
+import os
+
+
+assert os.access("test_filestat.py", os.F_OK) == True
+assert os.access("test_filestat.py-not", os.F_OK) == False