diff --git a/src/ChangeLog b/src/ChangeLog
index 662aa5232ab..ded14de2c41 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,7 @@
 2012-06-17  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* coding.c (produce_chars): Use ptrdiff_t, not int.
+
 	* xterm.c (x_draw_underwave): Check for integer overflow.
 	This pacifies gcc 4.7.0 -Wunsafe-loop-optimizations on x86-64.
 
diff --git a/src/coding.c b/src/coding.c
index ab13f0311c0..64826ae16b9 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -6765,7 +6765,8 @@ produce_chars (struct coding_system *coding, Lisp_Object translation_table,
 
       while (buf < buf_end)
 	{
-	  int c = *buf, i;
+	  int c = *buf;
+	  ptrdiff_t i;
 
 	  if (c >= 0)
 	    {