diff --git a/newlib/libc/include/sys/unistd.h b/newlib/libc/include/sys/unistd.h
index 5386bd49d..6aa5c5298 100644
--- a/newlib/libc/include/sys/unistd.h
+++ b/newlib/libc/include/sys/unistd.h
@@ -533,7 +533,8 @@ int	unlinkat (int, const char *, int);
  *  confstr values per IEEE Std 1003.1, 2004 Edition
  */
 
-#ifdef __CYGWIN__	/* Only defined on Cygwin for now. */
+/* Only defined on Cygwin and RTEMS for now. */
+#if defined (__CYGWIN__) || defined(__rtems__)
 #define _CS_PATH                               0
 #define _CS_POSIX_V7_ILP32_OFF32_CFLAGS        1
 #define _CS_POSIX_V6_ILP32_OFF32_CFLAGS       _CS_POSIX_V7_ILP32_OFF32_CFLAGS