diff --git a/src/ChangeLog b/src/ChangeLog
index 3a5a4c97628..1b518a6341c 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -52,6 +52,7 @@
 	* character.h (FETCH_STRING_CHAR_ADVANCE): Likewise.
 	* coding.c (emacs_mule_char, encode_invocation_designation):
 	Now static, since they're not used elsewhere.
+	(decode_coding_iso_2022): Add "default: abort ();" as a safety check.
 
 2011-03-06  Chong Yidong  <cyd@stupidchicken.com>
 
diff --git a/src/coding.c b/src/coding.c
index 4fdbd1fd752..c9d32489351 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -3899,6 +3899,10 @@ decode_coding_iso_2022 (struct coding_system *coding)
 	      }
 	      continue;
 	    }
+	  break;
+
+	default:
+	  abort ();
 	}
 
       if (cmp_status->state == COMPOSING_NO