diff --git a/include/nuttx/compiler.h b/include/nuttx/compiler.h
index 7cb9054f518..fa018859bfa 100644
--- a/include/nuttx/compiler.h
+++ b/include/nuttx/compiler.h
@@ -262,6 +262,16 @@
 
 #  define CONFIG_HAVE_INLINE 1
 
+/* ISO C11 supports anonymous (unnamed) structures and unions, added in
+ * GCC 4.6
+ */
+
+#  undef CONFIG_HAVE_ANONYMOUS_STRUCT
+#  if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 5)
+#    define CONFIG_HAVE_ANONYMOUS_STRUCT 1
+#    define CONFIG_HAVE_ANONYMOUS_UNION 1
+#  endif
+
 /* GCC supports both types double and long long */
 
 #  ifndef __clang__
@@ -351,6 +361,11 @@
 
 #  define reentrant_function __reentrant
 
+/* ISO C11 supports anonymous (unnamed) structures and unions.  Does SDCC? */
+
+#  undef CONFIG_HAVE_ANONYMOUS_STRUCT
+#  undef  CONFIG_HAVE_ANONYMOUS_UNION
+
 /* Indicate that a local variable is not used */
 
 #  define UNUSED(a) ((void)(a))
@@ -524,6 +539,13 @@
 #  undef  CONFIG_HAVE_INLINE
 #  define inline
 
+/* ISO C11 supports anonymous (unnamed) structures and unions.  Zilog does
+ * not support C11
+ */
+
+#  undef CONFIG_HAVE_ANONYMOUS_STRUCT
+#  undef  CONFIG_HAVE_ANONYMOUS_UNION
+
 /* Older Zilog compilers support both types double and long long, but the size
  * is 32-bits (same as long and single precision) so it is safer to say that
  * they are not supported.  Later versions are more ANSII compliant and
@@ -588,6 +610,11 @@
 
 #  undef CONFIG_HAVE_CXX14
 
+/* ISO C11 supports anonymous (unnamed) structures and unions.  Does ICCARM? */
+
+#  undef CONFIG_HAVE_ANONYMOUS_STRUCT
+#  undef  CONFIG_HAVE_ANONYMOUS_UNION
+
 /* Unknown compiler *********************************************************/
 
 #else
@@ -626,6 +653,8 @@
 #  undef  CONFIG_HAVE_DOUBLE
 #  undef  CONFIG_HAVE_LONG_DOUBLE
 #  undef  CONFIG_CAN_PASS_STRUCTS
+#  undef  CONFIG_HAVE_ANONYMOUS_STRUCT
+#  undef  CONFIG_HAVE_ANONYMOUS_UNION
 
 #  define UNUSED(a) ((void)(a))
 
diff --git a/include/poll.h b/include/poll.h
index fb6269e20c2..f6ec3ac97a0 100644
--- a/include/poll.h
+++ b/include/poll.h
@@ -116,11 +116,16 @@ struct pollfd
    * they are not available in C89.
    */
 
+#ifdef CONFIG_HAVE_ANONYMOUS_UNION
   union
   {
     int        fd;      /* The descriptor being polled */
     FAR void  *ptr;     /* The psock or file being polled */
   };
+#else
+  int          fd;      /* The descriptor being polled */
+  FAR void    *ptr;     /* The psock or file being polled */
+#endif
 
   FAR sem_t   *sem;     /* Pointer to semaphore used to post output event */
   pollevent_t  events;  /* The input event flags */