diff --git a/ChangeLog b/ChangeLog
index 8262f76206..50ab9e928b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Feb  4 12:44:13 2013  Koichi Sasada  <ko1@atdot.net>
+
+	* vm_dump.c (control_frame_dump): capitalize prefix of `ep'
+	  if `ep' points an env object.
+
 Mon Feb  4 04:20:00 2013  Zachary Scott  <zachary@zacharyscott.net>
 
 	* lib/English.rb: Add English module for RDoc to parse, then
diff --git a/vm_dump.c b/vm_dump.c
index 930c7b799a..04d9610aa9 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -117,7 +117,7 @@ control_frame_dump(rb_thread_t *th, rb_control_frame_t *cfp)
 	fprintf(stderr, "p:%04"PRIdPTRDIFF" ", pc);
     }
     fprintf(stderr, "s:%04"PRIdPTRDIFF" ", cfp->sp - th->stack);
-    fprintf(stderr, ep_in_heap == ' ' ? "e:%06"PRIdPTRDIFF" " : "e:%06"PRIxPTRDIFF" ", ep % 10000);
+    fprintf(stderr, ep_in_heap == ' ' ? "e:%06"PRIdPTRDIFF" " : "E:%06"PRIxPTRDIFF" ", ep % 10000);
     fprintf(stderr, "%-6s", magic);
     if (line) {
 	fprintf(stderr, " %s", posbuf);