diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 959600d7db..b7d0739d87 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2014-07-24  Tom Tromey  <tromey@redhat.com>
+
+	* environ.c (unset_in_environ): Make "var" const.
+	* environ.h (unset_in_environ): Update.
+
 2014-07-24  Tom Tromey  <tromey@redhat.com>
 
 	* cli/cli-dump.c (scan_expression_with_cleanup): Return const.
diff --git a/gdb/environ.c b/gdb/environ.c
index 7092a1a3c9..d661a01010 100644
--- a/gdb/environ.c
+++ b/gdb/environ.c
@@ -161,7 +161,7 @@ set_in_environ (struct gdb_environ *e, const char *var, const char *value)
 /* Remove the setting for variable VAR from environment E.  */
 
 void
-unset_in_environ (struct gdb_environ *e, char *var)
+unset_in_environ (struct gdb_environ *e, const char *var)
 {
   int len = strlen (var);
   char **vector = e->vector;
diff --git a/gdb/environ.h b/gdb/environ.h
index 43f6bd415e..5c4fac1a08 100644
--- a/gdb/environ.h
+++ b/gdb/environ.h
@@ -42,7 +42,7 @@ extern char *get_in_environ (const struct gdb_environ *, const char *);
 
 extern void set_in_environ (struct gdb_environ *, const char *, const char *);
 
-extern void unset_in_environ (struct gdb_environ *, char *);
+extern void unset_in_environ (struct gdb_environ *, const char *);
 
 extern char **environ_vector (struct gdb_environ *);