diff --git a/stdlib/3/fcntl.pyi b/stdlib/3/fcntl.pyi
index 4db594750..ecf066664 100644
--- a/stdlib/3/fcntl.pyi
+++ b/stdlib/3/fcntl.pyi
@@ -1,11 +1,94 @@
 # Stubs for fcntl
-
-# NOTE: These are incomplete!
-
+from typing import Any, IO, Union
 import typing
 
-FD_CLOEXEC = 0
-F_GETFD = 0
-F_SETFD = 0
+FASYNC = ...  # type: int
+FD_CLOEXEC = ...  # type: int
+DN_ACCESS = ...  # type: int
+DN_ATTRIB = ...  # type: int
+DN_CREATE = ...  # type: int
+DN_DELETE = ...  # type: int
+DN_MODIFY = ...  # type: int
+DN_MULTISHOT = ...  # type: int
+DN_RENAME = ...  # type: int
+F_DUPFD = ...  # type: int
+F_DUPFD_CLOEXEC = ...  # type: int
+F_FULLFSYNC = ...  # type: int
+F_EXLCK = ...  # type: int
+F_GETFD = ...  # type: int
+F_GETFL = ...  # type: int
+F_GETLEASE = ...  # type: int
+F_GETLK = ...  # type: int
+F_GETLK64 = ...  # type: int
+F_GETOWN = ...  # type: int
+F_NOCACHE = ...  # type: int
+F_GETSIG = ...  # type: int
+F_NOTIFY = ...  # type: int
+F_RDLCK = ...  # type: int
+F_SETFD = ...  # type: int
+F_SETFL = ...  # type: int
+F_SETLEASE = ...  # type: int
+F_SETLK = ...  # type: int
+F_SETLK64 = ...  # type: int
+F_SETLKW = ...  # type: int
+F_SETLKW64 = ...  # type: int
+F_SETOWN = ...  # type: int
+F_SETSIG = ...  # type: int
+F_SHLCK = ...  # type: int
+F_UNLCK = ...  # type: int
+F_WRLCK = ...  # type: int
+I_ATMARK = ...  # type: int
+I_CANPUT = ...  # type: int
+I_CKBAND = ...  # type: int
+I_FDINSERT = ...  # type: int
+I_FIND = ...  # type: int
+I_FLUSH = ...  # type: int
+I_FLUSHBAND = ...  # type: int
+I_GETBAND = ...  # type: int
+I_GETCLTIME = ...  # type: int
+I_GETSIG = ...  # type: int
+I_GRDOPT = ...  # type: int
+I_GWROPT = ...  # type: int
+I_LINK = ...  # type: int
+I_LIST = ...  # type: int
+I_LOOK = ...  # type: int
+I_NREAD = ...  # type: int
+I_PEEK = ...  # type: int
+I_PLINK = ...  # type: int
+I_POP = ...  # type: int
+I_PUNLINK = ...  # type: int
+I_PUSH = ...  # type: int
+I_RECVFD = ...  # type: int
+I_SENDFD = ...  # type: int
+I_SETCLTIME = ...  # type: int
+I_SETSIG = ...  # type: int
+I_SRDOPT = ...  # type: int
+I_STR = ...  # type: int
+I_SWROPT = ...  # type: int
+I_UNLINK = ...  # type: int
+LOCK_EX = ...  # type: int
+LOCK_MAND = ...  # type: int
+LOCK_NB = ...  # type: int
+LOCK_READ = ...  # type: int
+LOCK_RW = ...  # type: int
+LOCK_SH = ...  # type: int
+LOCK_UN = ...  # type: int
+LOCK_WRITE = ...  # type: int
 
-def fcntl(fd: int, op: int, arg: int = ...) -> int: ...
+_AnyFile = Union[int, IO[Any]]
+
+def fcntl(fd: _AnyFile,
+          cmd: int,
+          arg: Union[int, bytes] = ...) -> Union[int, bytes]: ...
+# TODO This function accepts any object supporting a buffer interface,
+# as arg, is there a better way to express this than bytes?
+def ioctl(fd: _AnyFile,
+          request: int,
+          arg: Union[int, bytes] = ...,
+          mutate_flag: bool = ...) -> Union[int, bytes]: ...
+def flock(fd: _AnyFile, operation: int) -> None: ...
+def lockf(fd: _AnyFile,
+          cmd: int,
+          len: int = ...,
+          start: int = ...,
+          whence: int = ...) -> Union[int, bytes]: ...