diff --git a/src/getchar.c b/src/getchar.c
index 6fecc1a..08c1a95 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -2785,7 +2785,6 @@
 	int	save_m_noremap;
 	int	save_m_silent;
 	char_u	*save_m_keys;
-	char_u	*save_m_str;
 #else
 # define save_m_noremap mp->m_noremap
 # define save_m_silent mp->m_silent
@@ -2834,7 +2833,6 @@
 	save_m_noremap = mp->m_noremap;
 	save_m_silent = mp->m_silent;
 	save_m_keys = NULL;  // only saved when needed
-	save_m_str = NULL;  // only saved when needed
 
 	/*
 	 * Handle ":map <expr>": evaluate the {rhs} as an expression.  Also
@@ -2851,8 +2849,7 @@
 	    may_garbage_collect = FALSE;
 
 	    save_m_keys = vim_strsave(mp->m_keys);
-	    save_m_str = vim_strsave(mp->m_str);
-	    map_str = eval_map_expr(save_m_str, NUL);
+	    map_str = eval_map_expr(mp, NUL);
 
 	    // The mapping may do anything, but we expect it to take care of
 	    // redrawing.  Do put the cursor back where it was.
@@ -2900,7 +2897,6 @@
 	}
 #ifdef FEAT_EVAL
 	vim_free(save_m_keys);
-	vim_free(save_m_str);
 #endif
 	*keylenp = keylen;
 	if (i == FAIL)
diff --git a/src/map.c b/src/map.c
index 336425a..181aa65 100644
--- a/src/map.c
+++ b/src/map.c
@@ -260,6 +260,7 @@
     {
 	mp->m_script_ctx.sc_sid = sid;
 	mp->m_script_ctx.sc_lnum = lnum;
+	mp->m_script_ctx.sc_version = in_vim9script() ? SCRIPT_VERSION_VIM9 : 0;
     }
     else
     {
@@ -1565,7 +1566,7 @@
 	    }
 #ifdef FEAT_EVAL
 	    if (mp->m_expr)
-		s = eval_map_expr(mp->m_str, c);
+		s = eval_map_expr(mp, c);
 	    else
 #endif
 		s = mp->m_str;
@@ -1600,7 +1601,7 @@
  */
     char_u *
 eval_map_expr(
-    char_u	*str,
+    mapblock_T	*mp,
     int		c)	    // NUL or typed character for abbreviation
 {
     char_u	*res;
@@ -1609,10 +1610,12 @@
     pos_T	save_cursor;
     int		save_msg_col;
     int		save_msg_row;
+    scid_T	save_sctx_sid = current_sctx.sc_sid;
+    int		save_sctx_version = current_sctx.sc_version;
 
     // Remove escaping of CSI, because "str" is in a format to be used as
     // typeahead.
-    expr = vim_strsave(str);
+    expr = vim_strsave(mp->m_str);
     if (expr == NULL)
 	return NULL;
     vim_unescape_csi(expr);
@@ -1625,12 +1628,22 @@
     save_cursor = curwin->w_cursor;
     save_msg_col = msg_col;
     save_msg_row = msg_row;
+    if (mp->m_script_ctx.sc_version == SCRIPT_VERSION_VIM9)
+    {
+	current_sctx.sc_sid = mp->m_script_ctx.sc_sid;
+	current_sctx.sc_version = SCRIPT_VERSION_VIM9;
+    }
+
+    // Note: the evaluation may make "mp" invalid.
     p = eval_to_string(expr, FALSE);
+
     --textwinlock;
     --ex_normal_lock;
     curwin->w_cursor = save_cursor;
     msg_col = save_msg_col;
     msg_row = save_msg_row;
+    current_sctx.sc_sid = save_sctx_sid;
+    current_sctx.sc_version = save_sctx_version;
 
     vim_free(expr);
 
diff --git a/src/proto/map.pro b/src/proto/map.pro
index 3592623..42ebd4b 100644
--- a/src/proto/map.pro
+++ b/src/proto/map.pro
@@ -10,7 +10,7 @@
 char_u *set_context_in_map_cmd(expand_T *xp, char_u *cmd, char_u *arg, int forceit, int isabbrev, int isunmap, cmdidx_T cmdidx);
 int ExpandMappings(regmatch_T *regmatch, int *num_file, char_u ***file);
 int check_abbr(int c, char_u *ptr, int col, int mincol);
-char_u *eval_map_expr(char_u *str, int c);
+char_u *eval_map_expr(mapblock_T *mp, int c);
 char_u *vim_strsave_escape_csi(char_u *p);
 void vim_unescape_csi(char_u *p);
 int makemap(FILE *fd, buf_T *buf);
diff --git a/src/testdir/test_vim9_import.vim b/src/testdir/test_vim9_import.vim
index 395265b..ddf5b82 100644
--- a/src/testdir/test_vim9_import.vim
+++ b/src/testdir/test_vim9_import.vim
@@ -1184,6 +1184,44 @@
   &rtp = save_rtp
 enddef
 
+def Test_autoload_mapping()
+  mkdir('Xdir/autoload', 'p')
+  var save_rtp = &rtp
+  exe 'set rtp^=' .. getcwd() .. '/Xdir'
+
+  var lines =<< trim END
+      vim9script autoload
+
+      g:toggle_loaded = 'yes'
+
+      export def Toggle(): string
+        return ":g:toggle_called = 'yes'\<CR>"
+      enddef
+  END
+  writefile(lines, 'Xdir/autoload/toggle.vim')
+
+  lines =<< trim END
+      vim9script
+
+      import autoload 'toggle.vim'
+
+      nnoremap <silent> <expr> tt toggle.Toggle() 
+  END
+  CheckScriptSuccess(lines)
+  assert_false(exists("g:toggle_loaded"))
+  assert_false(exists("g:toggle_called"))
+
+  feedkeys("tt", 'xt')
+  assert_equal('yes', g:toggle_loaded)
+  assert_equal('yes', g:toggle_called)
+
+  nunmap tt
+  unlet g:toggle_loaded
+  unlet g:toggle_called
+  delete('Xdir', 'rf')
+  &rtp = save_rtp
+enddef
+
 def Test_vim9script_autoload_fails()
   var lines =<< trim END
       vim9script autoload
diff --git a/src/version.c b/src/version.c
index f5e2ee0..27f6321 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4059,
+/**/
     4058,
 /**/
     4057,