diff --git a/src/nvim/keycodes.c b/src/nvim/keycodes.c
index ef067f68e2..9827604d67 100644
--- a/src/nvim/keycodes.c
+++ b/src/nvim/keycodes.c
@@ -850,7 +850,8 @@ char *vim_strsave_escape_ks(char *p)
 
 /// Remove escaping from K_SPECIAL characters.  Reverse of
 /// vim_strsave_escape_ks().  Works in-place.
-void vim_unescape_ks(char *p)
+/// Returns the number of bytes in the unescaped string.
+size_t vim_unescape_ks(char *p)
 {
   uint8_t *s = (uint8_t *)p;
   uint8_t *d = (uint8_t *)p;
@@ -864,4 +865,5 @@ void vim_unescape_ks(char *p)
     }
   }
   *d = NUL;
+  return (size_t)((char *)d - p);
 }
diff --git a/src/nvim/mapping.c b/src/nvim/mapping.c
index c9b8763354..3bebbb62eb 100644
--- a/src/nvim/mapping.c
+++ b/src/nvim/mapping.c
@@ -628,22 +628,28 @@ static int buf_do_map(int maptype, MapArguments *args, int mode, bool is_abbrev,
         // vi-compatible way.
         int same = -1;
 
-        const int first = vim_iswordp(lhs);
+        char keys_unescaped[MAXMAPLEN + 1];
+        xmemcpyz(keys_unescaped, lhs, (size_t)len);
+        size_t keys_unescaped_len = vim_unescape_ks(keys_unescaped);
+        const char *p = keys_unescaped;
+
+        const int first = vim_iswordp(p);
         int last = first;
-        const char *p = lhs + utfc_ptr2len(lhs);
+        MB_PTR_ADV(p);
         int n = 1;
-        while (p < lhs + len) {
+        while (p < keys_unescaped + keys_unescaped_len) {
           n++;                                  // nr of (multi-byte) chars
           last = vim_iswordp(p);                // type of last char
           if (same == -1 && last != first) {
             same = n - 1;                       // count of same char type
           }
-          p += utfc_ptr2len(p);
+          MB_PTR_ADV(p);
         }
         if (last && n > 2 && same >= 0 && same < n - 1) {
           retval = 1;
           goto theend;
         }
+
         // An abbreviation cannot contain white space.
         for (n = 0; n < len; n++) {
           if (ascii_iswhite(lhs[n])) {
@@ -1530,8 +1536,7 @@ bool check_abbr(int c, char *ptr, int col, int mincol)
       if (strchr(mp->m_keys, K_SPECIAL) != NULL) {
         // Might have K_SPECIAL escaped mp->m_keys.
         q = xstrdup(mp->m_keys);
-        vim_unescape_ks(q);
-        qlen = (int)strlen(q);
+        qlen = (int)vim_unescape_ks(q);
       }
       // find entries with right mode and keys
       int match = (mp->m_mode & State)
diff --git a/test/old/testdir/test_mapping.vim b/test/old/testdir/test_mapping.vim
index 2c6730bfed..5505d0f4d4 100644
--- a/test/old/testdir/test_mapping.vim
+++ b/test/old/testdir/test_mapping.vim
@@ -7,11 +7,41 @@ source term_util.vim
 
 func Test_abbreviation()
   new
-  " abbreviation with 0x80 should work
+
+  " abbreviation with 0x80 (full-id)
   inoreab чкпр   vim
   call feedkeys("Goчкпр \<Esc>", "xt")
   call assert_equal('vim ', getline('$'))
   iunab чкпр
+
+  " abbreviation with 0x80 (non-id)
+  inoreab abc⁀ abc^
+  inoreab ⁀ ^
+  call feedkeys("Goabc⁀ def⁀ ⁀ \<Esc>", "xt")
+  call assert_equal('abc^ def⁀ ^ ', getline('$'))
+  iunab abc⁀
+  iunab ⁀
+
+  " abbreviation with 0x9b (non-id)
+  inoreab abc； abc;
+  inoreab ； ;
+  call feedkeys("Goabc； def； ； \<Esc>", "xt")
+  call assert_equal('abc; def； ; ', getline('$'))
+  iunab abc；
+  iunab ；
+
+  " abbreviation with composing chars (end-id)
+  inoreab ..ã a^~
+  inoreab ..β̃ β^~
+  inoreab ..π̃ π^~
+  inoreab ..Λ̃ Λ^~
+  call feedkeys("Go..ã ..β̃ ..π̃ ..Λ̃ \<Esc>", "xt")
+  call assert_equal('a^~ β^~ π^~ Λ^~ ', getline('$'))
+  iunab ..ã
+  iunab ..β̃
+  iunab ..π̃
+  iunab ..Λ̃
+
   bwipe!
 endfunc