diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 81d3cb9..c673453 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -1498,6 +1498,27 @@
       let l = [11 , 22]
   END
   CheckScriptFailure(lines, 'E1068:')
+
+  lines =<< trim END
+    vim9script
+    let l: list<number> = [234, 'x']
+  END
+  CheckScriptFailure(lines, 'E1013:')
+  lines =<< trim END
+    vim9script
+    let l: list<number> = ['x', 234]
+  END
+  CheckScriptFailure(lines, 'E1013:')
+  lines =<< trim END
+    vim9script
+    let l: list<string> = ['x', 234]
+  END
+  CheckScriptFailure(lines, 'E1013:')
+  lines =<< trim END
+    vim9script
+    let l: list<string> = [234, 'x']
+  END
+  CheckScriptFailure(lines, 'E1013:')
 enddef
 
 def LambdaWithComments(): func
@@ -1679,6 +1700,27 @@
       let d = #{one: 1 , two: 2}
   END
   CheckScriptFailure(lines, 'E1068:')
+
+  lines =<< trim END
+    vim9script
+    let l: dict<number> = #{a: 234, b: 'x'}
+  END
+  CheckScriptFailure(lines, 'E1013:')
+  lines =<< trim END
+    vim9script
+    let l: dict<number> = #{a: 'x', b: 234}
+  END
+  CheckScriptFailure(lines, 'E1013:')
+  lines =<< trim END
+    vim9script
+    let l: dict<string> = #{a: 'x', b: 234}
+  END
+  CheckScriptFailure(lines, 'E1013:')
+  lines =<< trim END
+    vim9script
+    let l: dict<string> = #{a: 234, b: 'x'}
+  END
+  CheckScriptFailure(lines, 'E1013:')
 enddef
 
 let g:oneString = 'one'
diff --git a/src/version.c b/src/version.c
index ce5bfb0..132af7c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1451,
+/**/
     1450,
 /**/
     1449,
diff --git a/src/vim9type.c b/src/vim9type.c
index 9578597..318739b 100644
--- a/src/vim9type.c
+++ b/src/vim9type.c
@@ -214,11 +214,17 @@
 
     if (tv->v_type == VAR_LIST)
     {
+	listitem_T *li;
+
 	if (tv->vval.v_list == NULL || tv->vval.v_list->lv_first == NULL)
 	    return &t_list_empty;
 
-	// Use the type of the first member, it is the most specific.
+	// Use the common type of all members.
 	member_type = typval2type(&tv->vval.v_list->lv_first->li_tv, type_gap);
+	for (li = tv->vval.v_list->lv_first->li_next; li != NULL;
+							     li = li->li_next)
+	    common_type(typval2type(&li->li_tv, type_gap),
+					  member_type, &member_type, type_gap);
 	return get_list_type(member_type, type_gap);
     }
 
@@ -231,10 +237,13 @@
 				   || tv->vval.v_dict->dv_hashtab.ht_used == 0)
 	    return &t_dict_empty;
 
-	// Use the type of the first value, it is the most specific.
+	// Use the common type of all values.
 	dict_iterate_start(tv, &iter);
 	dict_iterate_next(&iter, &value);
 	member_type = typval2type(value, type_gap);
+	while (dict_iterate_next(&iter, &value) != NULL)
+	    common_type(typval2type(value, type_gap),
+					  member_type, &member_type, type_gap);
 	return get_dict_type(member_type, type_gap);
     }