diff --git a/newlib/libc/include/sys/_types.h b/newlib/libc/include/sys/_types.h
index 762dfedd0..ce1aa7019 100644
--- a/newlib/libc/include/sys/_types.h
+++ b/newlib/libc/include/sys/_types.h
@@ -43,6 +43,10 @@ typedef unsigned short __uid_t;
 typedef unsigned short __gid_t;
 #endif
 
+#ifndef __machine_id_t_defined
+typedef __uint32_t __id_t;
+#endif
+
 #ifndef __machine_off64_t_defined
 __extension__ typedef long long _off64_t;
 #endif
diff --git a/newlib/libc/include/sys/types.h b/newlib/libc/include/sys/types.h
index 316ee9ac4..d093578c7 100644
--- a/newlib/libc/include/sys/types.h
+++ b/newlib/libc/include/sys/types.h
@@ -134,6 +134,11 @@ typedef	char *	caddr_t;
 #define __caddr_t_defined
 #endif
 
+#ifndef _ID_T_DECLARED
+typedef	__id_t		id_t;		/* can hold a uid_t or pid_t */
+#define	_ID_T_DECLARED
+#endif
+
 #ifndef __CYGWIN__
 #if defined(__MS_types__) || defined(__rtems__) || \
     defined(__sparc__) || defined(__SPU__)
diff --git a/winsup/cygwin/include/cygwin/types.h b/winsup/cygwin/include/cygwin/types.h
index f9ed4b66d..bfffc5dbe 100644
--- a/winsup/cygwin/include/cygwin/types.h
+++ b/winsup/cygwin/include/cygwin/types.h
@@ -65,12 +65,6 @@ typedef __uint32_t __ino32_t;
 typedef __uint64_t ino_t;
 #endif /*__ino_t_defined*/
 
-/* Generic ID type, must match at least pid_t, uid_t and gid_t in size. */
-#ifndef __id_t_defined
-#define __id_t_defined
-typedef __uint32_t id_t;
-#endif /* __id_t_defined */
-
 #if defined (__INSIDE_CYGWIN__) && !defined (__x86_64__)
 struct __flock32 {
 	short	 l_type;	/* F_RDLCK, F_WRLCK, or F_UNLCK */