diff --git a/py/objdict.c b/py/objdict.c
index 7fad5fc8f4..baad8a1b9e 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -190,6 +190,17 @@ STATIC mp_obj_t dict_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_
                 return mp_const_false;
             }
         }
+        #if MICROPY_CPYTHON_COMPAT
+        case MP_BINARY_OP_INPLACE_OR:
+        case MP_BINARY_OP_OR: {
+            if (op == MP_BINARY_OP_OR) {
+                lhs_in = mp_obj_dict_copy(lhs_in);
+            }
+            mp_obj_t dicts[2] = {lhs_in, rhs_in};
+            dict_update(2, dicts, (mp_map_t *)&mp_const_empty_map);
+            return lhs_in;
+        }
+        #endif
         default:
             // op not supported
             return MP_OBJ_NULL;
diff --git a/tests/basics/dict_union.py b/tests/basics/dict_union.py
new file mode 100644
index 0000000000..606b1c4c52
--- /dev/null
+++ b/tests/basics/dict_union.py
@@ -0,0 +1,36 @@
+# Test dictionary union.
+#
+# The tests sort the resulting dictionaries for now, since map insertion
+# order is not implemented in MicroPython.
+
+try:
+    {} | {}
+except TypeError:
+    print("SKIP")
+    raise SystemExit
+
+
+def print_sorted_dict(d):
+    print(sorted(d.items()))
+
+
+def test_union(a, b):
+    print_sorted_dict(a | b)
+    print_sorted_dict(b | a)
+    a |= a
+    print_sorted_dict(a)
+    a |= b
+    print_sorted_dict(a)
+
+
+d = {}
+e = {}
+test_union(d, e)
+
+d = {1: "apple"}
+e = {1: "cheese"}
+test_union(d, e)
+
+d = {"spam": 1, "eggs": 2, "cheese": 3}
+e = {"cheese": "cheddar", "aardvark": "Ethel"}
+test_union(d, e)
diff --git a/tests/basics/dict_union.py.exp b/tests/basics/dict_union.py.exp
new file mode 100644
index 0000000000..7a8f83bd54
--- /dev/null
+++ b/tests/basics/dict_union.py.exp
@@ -0,0 +1,12 @@
+[]
+[]
+[]
+[]
+[(1, 'cheese')]
+[(1, 'apple')]
+[(1, 'apple')]
+[(1, 'cheese')]
+[('aardvark', 'Ethel'), ('cheese', 'cheddar'), ('eggs', 2), ('spam', 1)]
+[('aardvark', 'Ethel'), ('cheese', 3), ('eggs', 2), ('spam', 1)]
+[('cheese', 3), ('eggs', 2), ('spam', 1)]
+[('aardvark', 'Ethel'), ('cheese', 'cheddar'), ('eggs', 2), ('spam', 1)]