diff --git a/src/ChangeLog b/src/ChangeLog
index 275d7e08a76..54fe58d1118 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,7 @@
 2011-06-14  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* bytecode.c (exec_byte_code): Use ptrdiff_t, not int, for vector length.
+
 	* eval.c, doprnt.c (SIZE_MAX): Remove; inttypes.h defines this now.
 
 	Variadic C functions now count arguments with ptrdiff_t.
diff --git a/src/bytecode.c b/src/bytecode.c
index adc9352fb6e..58b26c79b84 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -444,7 +444,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
   /* Lisp_Object v1, v2; */
   Lisp_Object *vectorp;
 #ifdef BYTE_CODE_SAFE
-  int const_length;
+  ptrdiff_t const_length;
   Lisp_Object *stacke;
   int bytestr_length;
 #endif