diff --git a/bits/dirent.h b/bits/dirent.h
index 7b79a53..69a7892 100644
--- a/bits/dirent.h
+++ b/bits/dirent.h
@@ -32,7 +32,7 @@ struct dirent
     unsigned char d_namlen;	/* Length of the file name.  */
 
     /* Only this member is in the POSIX standard.  */
-    char d_name[1];		/* File name (actually longer).  */
+    __flexarray (d_name, char, 1); /* File name.  */
   };
 
 #ifdef __USE_LARGEFILE64
@@ -42,8 +42,7 @@ struct dirent64
     unsigned short int d_reclen;
     unsigned char d_type;
     unsigned char d_namlen;
-
-    char d_name[1];
+    __flexarray (d_name, char, 1); /* File name.  */
   };
 #endif
 
diff --git a/include/features.h b/include/features.h
index 9514d35..ca162d3 100644
--- a/include/features.h
+++ b/include/features.h
@@ -45,6 +45,7 @@
    _THREAD_SAFE		Same as _REENTRANT, often used by other systems.
    _FORTIFY_SOURCE	If set to numeric value > 0 additional security
 			measures are defined, according to level.
+   _FLEXARRAY_SOURCE	Select flexible array data structures when applicable.
 
    The `-ansi' switch to the GNU C compiler, and standards conformance
    options such as `-std=c99', define __STRICT_ANSI__.  If none of
@@ -80,6 +81,7 @@
    __USE_GNU		Define GNU extensions.
    __USE_REENTRANT	Define reentrant/thread-safe *_r functions.
    __USE_FORTIFY_LEVEL	Additional security measures used, according to level.
+   __USE_FLEXARRAY	Use flexible arrays for data structures.
 
    The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
    defined by this file unconditionally.  `__GNU_LIBRARY__' is provided
@@ -117,6 +119,7 @@
 #undef	__USE_GNU
 #undef	__USE_REENTRANT
 #undef	__USE_FORTIFY_LEVEL
+#undef	__USE_FLEXARRAY
 #undef	__KERNEL_STRICT_NAMES
 
 /* Suppress kernel-name space pollution unless user expressedly asks
@@ -341,6 +344,10 @@
 # define __USE_FORTIFY_LEVEL 0
 #endif
 
+#ifdef _FLEXARRAY_SOURCE
+# define __USE_FLEXARRAY 1
+#endif
+
 /* Get definitions of __STDC_* predefined macros, if the compiler has
    not preincluded this header automatically.  */
 #include <stdc-predef.h>
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 7fd4154..facfdc3 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -157,10 +157,29 @@
 #  else
 /* Some other non-C99 compiler.  Approximate with [1].  */
 #   define __flexarr	[1]
+#   define __flexarray(id, type, size) type id[size]
 #  endif
 # endif
 #endif
 
+/* Declare a structure member named ID, with type "array of TYPE", and
+   with actual size unspecified but with nominal size SIZE for the
+   benefit of traditional applications.  If the application is
+   compiled with _FLEXARRAY_SOURCE and if the compiler is C99 or
+   better, model this as a flexible array.  Otherwise, model it as a
+   fixed-size array of size SIZE (followed by a flexible array
+   afterwards, if C99, for the benefit of source-code analyzers that
+   can use this as a cue that the array is really varying-size).  The
+   fixed-size array is for compatibility with programs that unwisely
+   take the size of structures that contain flexible arrays, and which
+   rely on traditional glibc which uses fixed-size arrays.  */
+#ifndef __flexarray
+# ifdef __USE_FLEXARRAY
+#  define __flexarray(id, type, size) type id[]
+# else
+#  define __flexarray(id, type, size) type id[size]; type __flexarray __flexarr
+# endif
+#endif
 
 /* __asm__ ("xyz") is used throughout the headers to rename functions
    at the assembly language level.  This is wrapped by the __REDIRECT
diff --git a/sysdeps/nacl/bits/dirent.h b/sysdeps/nacl/bits/dirent.h
index d4eb7fe..2e38a58 100644
--- a/sysdeps/nacl/bits/dirent.h
+++ b/sysdeps/nacl/bits/dirent.h
@@ -30,7 +30,7 @@ struct dirent
     unsigned short int d_reclen; /* Length of the whole `struct dirent'.  */
 
     /* Only this member is in the POSIX standard.  */
-    char d_name[256];		/* We must not include limits.h! */
+    __flexarray (d_name, char, 256); /* We must not include limits.h! */
   };
 
 #ifdef __USE_LARGEFILE64
@@ -42,7 +42,7 @@ struct dirent64
     unsigned short int d_reclen; /* Length of the whole `struct dirent'.  */
 
     /* Only this member is in the POSIX standard.  */
-    char d_name[256];		/* We must not include limits.h! */
+    __flexarray (d_name, char, 256); /* We must not include limits.h! */
   };
 #endif
 
diff --git a/sysdeps/unix/sysv/linux/alpha/bits/dirent.h b/sysdeps/unix/sysv/linux/alpha/bits/dirent.h
index 98d297e..2470d0f 100644
--- a/sysdeps/unix/sysv/linux/alpha/bits/dirent.h
+++ b/sysdeps/unix/sysv/linux/alpha/bits/dirent.h
@@ -29,7 +29,7 @@ struct dirent
     __off_t d_off;
     unsigned short int d_reclen;
     unsigned char d_type;
-    char d_name[256];		/* We must not include limits.h! */
+    __flexarray (d_name, char, 256); /* We must not include limits.h! */
   };
 
 #ifdef __USE_LARGEFILE64
@@ -40,7 +40,7 @@ struct dirent64
     __off64_t d_off;
     unsigned short int d_reclen;
     unsigned char d_type;
-    char d_name[256];		/* We must not include limits.h! */
+    __flexarray (d_name, char, 256); /* We must not include limits.h! */
   };
 #endif
 
diff --git a/sysdeps/unix/sysv/linux/bits/dirent.h b/sysdeps/unix/sysv/linux/bits/dirent.h
index 31b1961..b7137e0 100644
--- a/sysdeps/unix/sysv/linux/bits/dirent.h
+++ b/sysdeps/unix/sysv/linux/bits/dirent.h
@@ -30,7 +30,7 @@ struct dirent
 #endif
     unsigned short int d_reclen;
     unsigned char d_type;
-    char d_name[256];		/* We must not include limits.h! */
+    __flexarray (d_name, char, 256); /* We must not include limits.h! */
   };
 
 #ifdef __USE_LARGEFILE64
@@ -40,7 +40,7 @@ struct dirent64
     __off64_t d_off;
     unsigned short int d_reclen;
     unsigned char d_type;
-    char d_name[256];		/* We must not include limits.h! */
+    __flexarray (d_name, char, 256); /* We must not include limits.h! */
   };
 #endif