1 files changed, 15 insertions, 10 deletions

diff --git a/src/keyboard.c b/src/keyboard.c
index ed8e71fd0a7..0fad633581d 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -9642,22 +9642,26 @@ read_key_sequence (Lisp_Object *keybuf, int bufsize, Lisp_Object prompt,
          use the corresponding lower-case letter instead.  */
       if (NILP (current_binding)
           && /* indec.start >= t && fkey.start >= t && */ keytran.start >= t
-          && INTEGERP (key)
-          && ((CHARACTERP (make_number (XINT (key) & ~CHAR_MODIFIER_MASK))
-               && uppercasep (XINT (key) & ~CHAR_MODIFIER_MASK))
-              || (XINT (key) & shift_modifier)))
+          && INTEGERP (key))
         {
           Lisp_Object new_key;
+          int k = XINT (key);
+
+          if (k & shift_modifier)
+            XSETINT (new_key, k & ~shift_modifier);
+          else if (CHARACTERP (make_number (k & ~CHAR_MODIFIER_MASK)))
+            {
+              int dc = downcase(k & ~CHAR_MODIFIER_MASK);
+              if (dc == (k & ~CHAR_MODIFIER_MASK))
+                goto not_upcase;
+              XSETINT (new_key, dc | (k & CHAR_MODIFIER_MASK));
+            }
+          else
+            goto not_upcase;
 
           original_uppercase = key;
           original_uppercase_position = t - 1;
 
-          if (XINT (key) & shift_modifier)
-            XSETINT (new_key, XINT (key) & ~shift_modifier);
-          else
-            XSETINT (new_key, (downcase (XINT (key) & ~CHAR_MODIFIER_MASK)
-                               | (XINT (key) & CHAR_MODIFIER_MASK)));
-
           /* We have to do this unconditionally, regardless of whether
              the lower-case char is defined in the keymaps, because they
              might get translated through function-key-map.  */
@@ -9668,6 +9672,7 @@ read_key_sequence (Lisp_Object *keybuf, int bufsize, Lisp_Object prompt,
           goto replay_sequence;
         }
 
+    not_upcase:
       if (NILP (current_binding)
           && help_char_p (EVENT_HEAD (key)) && t > 1)
             {