diff --git a/src/dict.c b/src/dict.c
index 27cde11..f39be72 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -109,8 +109,6 @@
     hashtab_free_contents(&d->dv_hashtab);
     free_type(d->dv_type);
     d->dv_type = NULL;
-    free_type(d->dv_decl_type);
-    d->dv_decl_type = NULL;
 }
 
 /*
diff --git a/src/list.c b/src/list.c
index 6ad3e92..aadc723 100644
--- a/src/list.c
+++ b/src/list.c
@@ -271,7 +271,6 @@
 	l->lv_used_next->lv_used_prev = l->lv_used_prev;
 
     free_type(l->lv_type);
-    free_type(l->lv_decl_type);
     vim_free(l);
 }
 
@@ -1026,8 +1025,6 @@
 	// The type will change.
 	free_type(l->lv_type);
 	l->lv_type = NULL;
-	free_type(l->lv_decl_type);
-	l->lv_decl_type = NULL;
     }
     else
     {
@@ -1223,7 +1220,6 @@
     if (copy != NULL)
     {
 	copy->lv_type = alloc_type(orig->lv_type);
-	copy->lv_decl_type = alloc_type(orig->lv_decl_type);
 	if (copyID != 0)
 	{
 	    // Do this before adding the items, because one of the items may
diff --git a/src/structs.h b/src/structs.h
index 7d040eb..2da16bf 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1513,7 +1513,6 @@
 	} mat;
     } lv_u;
     type_T	*lv_type;	// current type, allocated by alloc_type()
-    type_T	*lv_decl_type;	// declared type, allocated by alloc_type()
     list_T	*lv_copylist;	// copied list used by deepcopy()
     list_T	*lv_used_next;	// next list in used lists list
     list_T	*lv_used_prev;	// previous list in used lists list
@@ -1578,7 +1577,6 @@
     int		dv_copyID;	// ID used by deepcopy()
     hashtab_T	dv_hashtab;	// hashtab that refers to the items
     type_T	*dv_type;	// current type, allocated by alloc_type()
-    type_T	*dv_decl_type;	// declared type, allocated by alloc_type()
     dict_T	*dv_copydict;	// copied dict used by deepcopy()
     dict_T	*dv_used_next;	// next dict in used dicts list
     dict_T	*dv_used_prev;	// previous dict in used dicts list
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index d957c15..eb86a03 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -979,6 +979,10 @@
       var res: list<dict<any>>
       extend(res, mapnew([1, 2], (_, v) => ({})))
       assert_equal([{}, {}], res)
+
+      var dany: dict<any> = {a: 0}
+      dany->extend({b: 'x'})
+      assert_equal({a: 0, b: 'x'}, dany)
   END
   CheckDefAndScriptSuccess(lines)
 
@@ -2151,9 +2155,29 @@
   CheckDefAndScriptFailure(['map(1, "1")'], ['E1013: Argument 1: type mismatch, expected list<any> but got number', 'E1251: List, Dictionary, Blob or String required for argument 1'])
 
   # type of dict remains dict<any> even when type of values changes
-  var d: dict<any> = {a: 0}
-  d->map((k, v) => true)
-  d->map((k, v) => 'x')
+  # same for list
+  var lines =<< trim END
+      var d: dict<any> = {a: 0}
+      d->map((k, v) => true)
+      d->map((k, v) => 'x')
+      assert_equal({a: 'x'}, d)
+
+      d = {a: 0}
+      g:gd = d
+      map(g:gd, (k, v) => true)
+      assert_equal({a: true}, g:gd)
+
+      var l: list<any> = [0]
+      l->map((k, v) => true)
+      l->map((k, v) => 'x')
+      assert_equal(['x'], l)
+
+      l = [1]
+      g:gl = l
+      map(g:gl, (k, v) => true)
+      assert_equal([true], g:gl)
+  END
+  CheckDefAndScriptSuccess(lines)
 enddef
 
 def Test_map_failure()
@@ -2175,6 +2199,13 @@
   CheckScriptFailure(lines, 'E1013:')
   au! BufReadPost
   delete('Xtmpfile')
+
+  lines =<< trim END
+      var d: dict<number> = {a: 1}
+      g:gd = d
+      map(g:gd, (k, v) => true)
+  END
+  CheckDefExecAndScriptFailure(lines, 'E1012: Type mismatch; expected number but got bool')
 enddef
 
 def Test_map_function_arg()
diff --git a/src/testdir/test_vim9_disassemble.vim b/src/testdir/test_vim9_disassemble.vim
index d4a5309..3a7642f 100644
--- a/src/testdir/test_vim9_disassemble.vim
+++ b/src/testdir/test_vim9_disassemble.vim
@@ -455,6 +455,7 @@
         '\d\+ CHECKTYPE string stack\[-1\] arg 2\_s*' ..
         '\d\+ STORE $1\_s*' ..
         '\d\+ SLICE 2\_s*' ..
+        '\d\+ SETTYPE list<any>\_s*' ..
         '\d\+ STORE $2\_s*' ..
         '\d\+ RETURN void',
         res)
diff --git a/src/version.c b/src/version.c
index 4d15dbf..170c0c2 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3997,
+/**/
     3996,
 /**/
     3995,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index a243e64..cccf02c 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -2279,14 +2279,12 @@
 		// ":const var": lock the value, but not referenced variables
 		generate_LOCKCONST(cctx);
 
-	    if (is_decl
-		    && (lhs.lhs_type->tt_type == VAR_DICT
+	    if ((lhs.lhs_type->tt_type == VAR_DICT
 					  || lhs.lhs_type->tt_type == VAR_LIST)
 		    && lhs.lhs_type->tt_member != NULL
 		    && lhs.lhs_type->tt_member != &t_unknown)
 		// Set the type in the list or dict, so that it can be checked,
-		// also in legacy script.  Not for "list<any> = val", then the
-		// type of "val" is used.
+		// also in legacy script.
 		generate_SETTYPE(cctx, lhs.lhs_type);
 
 	    if (!skip_store && generate_store_lhs(cctx, &lhs,