diff --git a/src/ChangeLog b/src/ChangeLog
index 377a2ecc7..a2e3891c6 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,8 @@
 2001-05-16  Pavel Roskin  <proski@gnu.org>
 
+	* subshell.c: Define _GNU_SOURCE to enable prototypes for
+	allocating pseudo-terminals on GNU systems.
+
 	* subshell.c (init_subshell_child): New function to initialize
 	child process and run subshell. Code moved from ...
 	(init_subshell): ... here.
diff --git a/src/subshell.c b/src/subshell.c
index 4cfe8fd45..c862faa03 100644
--- a/src/subshell.c
+++ b/src/subshell.c
@@ -24,6 +24,10 @@
 
 /* {{{ Declarations */
 
+#ifndef _GNU_SOURCE
+#   define _GNU_SOURCE 1
+#endif
+
 #include <stdio.h>      
 #include <stdlib.h>	/* For errno, putenv, etc.	      */
 #include <errno.h>	/* For errno on SunOS systems	      */