diff --git a/src/ChangeLog b/src/ChangeLog
index 1956d602e6a..5956eea1c51 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2012-08-18  Alp Aker  <alp.tekin.aker@gmail.com>
+
+	* nsfont.m (ns_ascii_average_width): Ensure the string
+	ascii_printable is initialized with a null-terminated character
+	array.  Otherwise, it can contain undesired extra characters.
+
 2012-08-18  Paul Eggert  <eggert@cs.ucla.edu>
 
 	port new setting code to Sun C 5.8 2005/10/13
diff --git a/src/nsfont.m b/src/nsfont.m
index 1f8d28cd238..412a6777c64 100644
--- a/src/nsfont.m
+++ b/src/nsfont.m
@@ -270,10 +270,11 @@ static void ns_glyph_metrics (struct nsfont_info *font_info,
 
   if (!ascii_printable)
     {
-      char chars[95];
+      char chars[96];
       int ch;
       for (ch = 0; ch < 95; ch++)
 	chars[ch] = ' ' + ch;
+      chars[95] = '\0';
 
       ascii_printable = [[NSString alloc] initWithFormat: @"%s", chars];
     }