1 files changed, 5 insertions, 2 deletions

diff --git a/src/callint.c b/src/callint.c
index e5ec3d7d931..cddd92c8a94 100644
--- a/src/callint.c
+++ b/src/callint.c
@@ -27,6 +27,7 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "keyboard.h"
 #include "window.h"
 #include "keymap.h"
+#include "character.h"
 
 Lisp_Object Qminus, Qplus;
 Lisp_Object Qcall_interactively;
@@ -786,8 +787,10 @@ invoke it.  If KEYS is omitted or nil, the return value of
              if anyone tries to define one here.  */
         case '+':
         default:
-          error ("Invalid control letter `%c' (%03o) in interactive calling string",
-                 *tem, (unsigned char) *tem);
+          error ("Invalid control letter `%c' (#o%03o, #x%04x) in interactive calling string",
+                 STRING_CHAR ((unsigned char *) tem),
+                 (unsigned) STRING_CHAR ((unsigned char *) tem),
+                 (unsigned) STRING_CHAR ((unsigned char *) tem));
         }
 
       if (varies[i] == 0)