diff --git a/Lib/test/test_set.py b/Lib/test/test_set.py
--- a/Lib/test/test_set.py
+++ b/Lib/test/test_set.py
@@ -387,6 +387,21 @@
         t = {1,2,3}
         self.assertEqual(s, t)
 
+    def test_set_literal_insertion_order(self):
+        # SF Issue #26020 -- Expect left to right insertion
+        s = {1, 1.0, True}
+        self.assertEqual(len(s), 1)
+        stored_value = s.pop()
+        self.assertEqual(type(stored_value), int)
+
+    def test_set_literal_evaluation_order(self):
+        # Expect left to right expression evaluation
+        events = []
+        def record(obj):
+            events.append(obj)
+        s = {record(1), record(2), record(3)}
+        self.assertEqual(events, [1, 2, 3])
+
     def test_hash(self):
         self.assertRaises(TypeError, hash, self.s)
 
diff --git a/Python/ceval.c b/Python/ceval.c
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2536,14 +2536,16 @@
         TARGET(BUILD_SET) {
             PyObject *set = PySet_New(NULL);
             int err = 0;
+            int i;
             if (set == NULL)
                 goto error;
-            while (--oparg >= 0) {
-                PyObject *item = POP();
+            for (i = oparg; i > 0; i--) {
+                PyObject *item = PEEK(i);
                 if (err == 0)
                     err = PySet_Add(set, item);
                 Py_DECREF(item);
             }
+            STACKADJ(-oparg);
             if (err != 0) {
                 Py_DECREF(set);
                 goto error;