1 files changed, 14 insertions, 7 deletions

diff --git a/src/keymap.c b/src/keymap.c
index 0169276bef9..c461fdddbbc 100644
--- a/src/keymap.c
+++ b/src/keymap.c
@@ -1216,13 +1216,20 @@ binding KEY to DEF is added at the front of KEYMAP.  */)
 
       keymap = get_keymap (cmd, 0, 1);
       if (!CONSP (keymap))
-        /* We must use Fkey_description rather than just passing key to
-           error; key might be a vector, not a string.  */
-        error ("Key sequence %s starts with non-prefix key %s",
-               SDATA (Fkey_description (key, Qnil)),
-               SDATA (Fkey_description (Fsubstring (key, make_number (0),
-                                                    make_number (idx)),
-                                        Qnil)));
+        {
+          const char *trailing_esc = ((EQ (c, meta_prefix_char) && metized)
+                                      ? (idx == 0 ? "ESC" : " ESC")
+                                      : "");
+
+          /* We must use Fkey_description rather than just passing key to
+             error; key might be a vector, not a string.  */
+          error ("Key sequence %s starts with non-prefix key %s%s",
+                 SDATA (Fkey_description (key, Qnil)),
+                 SDATA (Fkey_description (Fsubstring (key, make_number (0),
+                                                      make_number (idx)),
+                                          Qnil)),
+                 trailing_esc);
+        }
     }
 }