diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 0e91c480fff..0c9a16d9dde 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2009-03-16  Kenichi Handa  <handa@m17n.org>
+
+	* international/ccl.el (ccl-compile-if): Signal an error for
+	invalid operator.
+
 2009-03-16  Chong Yidong  <cyd@stupidchicken.com>
 
 	* minibuffer.el (read-file-name): Doc fix.
diff --git a/lisp/international/ccl.el b/lisp/international/ccl.el
index 1d212afd519..c5088c8c9e5 100644
--- a/lisp/international/ccl.el
+++ b/lisp/international/ccl.el
@@ -505,6 +505,8 @@ If READ-FLAG is non-nil, this statement has the form
 	    (op (get (nth 1 condition) 'ccl-arith-code))
 	    (arg (nth 2 condition)))
 	(ccl-check-register rrr cmd)
+	(or (integerp op)
+	    (error "CCL: invalid operator: %s" (nth 1 condition)))
 	(if (integerp arg)
 	    (progn
 	      (ccl-embed-code (if read-flag 'read-jump-cond-expr-const