diff --git a/lib-src/ChangeLog b/lib-src/ChangeLog
index fe90917a70b..464b9e37359 100644
--- a/lib-src/ChangeLog
+++ b/lib-src/ChangeLog
@@ -1,3 +1,8 @@
+2012-08-19  Paul Eggert  <eggert@cs.ucla.edu>
+
+	Rely on <unistd.h> to declare 'environ'.
+	* emacsclient.c (environ): Remove decl.
+
 2012-08-17  Juanma Barranquero  <lekktu@gmail.com>
 
 	* makefile.w32-in ($(BLD)/regex.$(O)): Update dependencies.
diff --git a/lib-src/emacsclient.c b/lib-src/emacsclient.c
index 20afe1cad11..07300dbf249 100644
--- a/lib-src/emacsclient.c
+++ b/lib-src/emacsclient.c
@@ -1584,11 +1584,6 @@ main (int argc, char **argv)
   /* Send over our environment and current directory. */
   if (!current_frame)
     {
-#ifndef WINDOWSNT
-      /* This is defined in stdlib.h on MS-Windows.  It's defined in
-	 unistd.h on some POSIX hosts, but not all (Bug#10155).  */
-      extern char **environ;
-#endif
       int i;
       for (i = 0; environ[i]; i++)
         {
diff --git a/src/ChangeLog b/src/ChangeLog
index e922ede7a0c..fa3eaa281d7 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,12 @@
 2012-08-19  Paul Eggert  <eggert@cs.ucla.edu>
 
+	Rely on <unistd.h> to declare 'environ',
+	as gnulib does this if the system doesn't.
+	* callproc.c, editfns.c, process.c (environ) [!USE_CRT_DLL]:
+	* emacs.c (environ) [DOUG_LEA_MALLOC]:
+	* vm-limit.c (environ) [ORDINARY_LINK]: Remove decl.
+	* vm-limit.c: Include <unistd.h>, for 'environ'.
+
 	* unexaix.c, unexcoff.c: Include "mem-limits.h".
 	(start_of_data): Remove decl; mem-limits.h provides it.
 
diff --git a/src/callproc.c b/src/callproc.c
index 10a80168fb2..4bf1da04e1a 100644
--- a/src/callproc.c
+++ b/src/callproc.c
@@ -65,10 +65,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "nsterm.h"
 #endif
 
-#ifndef USE_CRT_DLL
-extern char **environ;
-#endif
-
 #ifdef HAVE_SETPGID
 #if !defined (USG)
 #undef setpgrp
diff --git a/src/editfns.c b/src/editfns.c
index c4725aa0ff3..fa57edead28 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -58,10 +58,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "window.h"
 #include "blockinput.h"
 
-#ifndef USE_CRT_DLL
-extern char **environ;
-#endif
-
 #define TM_YEAR_BASE 1900
 
 #ifdef WINDOWSNT
diff --git a/src/emacs.c b/src/emacs.c
index 8d458c612cc..9e7efcabbf7 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -642,10 +642,6 @@ argmatch (char **argv, int argc, const char *sstr, const char *lstr,
 static void
 malloc_initialize_hook (void)
 {
-#ifndef USE_CRT_DLL
-  extern char **environ;
-#endif
-
   if (initialized)
     {
       if (!malloc_using_checking)
diff --git a/src/process.c b/src/process.c
index ea463cd9187..7f6f6bafbea 100644
--- a/src/process.c
+++ b/src/process.c
@@ -1623,9 +1623,6 @@ create_process (Lisp_Object process, char **new_argv, Lisp_Object current_dir)
   /* Use volatile to protect variables from being clobbered by longjmp.  */
   volatile int forkin, forkout;
   volatile int pty_flag = 0;
-#ifndef USE_CRT_DLL
-  extern char **environ;
-#endif
 
   inchannel = outchannel = -1;
 
diff --git a/src/vm-limit.c b/src/vm-limit.c
index c313a900f2c..cf697b56fdf 100644
--- a/src/vm-limit.c
+++ b/src/vm-limit.c
@@ -18,6 +18,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <config.h>
 #include <setjmp.h>
+#include <unistd.h> /* for 'environ', on AIX */
 #include "lisp.h"
 #include "mem-limits.h"
 
@@ -268,7 +269,6 @@ start_of_data (void)
    * is known to live at or near the start of the system crt0.c, and
    * we don't sweat the handful of bytes that might lose.
    */
-  extern char **environ;
   return ((POINTER) &environ);
 #else
   extern int data_start;