diff --git a/msgpack_pack.c b/msgpack_pack.c
index 57887c1..85d2cd4 100644
--- a/msgpack_pack.c
+++ b/msgpack_pack.c
@@ -343,7 +343,7 @@ static inline void msgpack_serialize_array(smart_str *buf, zval *val, HashTable
                 zval *data_noref, *data = zend_hash_index_find(ht, i);
 
                 if (!data) {
-                    MSGPACK_WARNING("[msgpack (%s) array index %u is not set", __FUNCTION__, i);
+                    MSGPACK_WARNING("[msgpack] (%s) array index %u is not set", __FUNCTION__, i);
                     msgpack_pack_nil(buf);
                     continue;
                 }
diff --git a/msgpack_unpack.c b/msgpack_unpack.c
index 9b3cc3b..30e1d9e 100644
--- a/msgpack_unpack.c
+++ b/msgpack_unpack.c
@@ -692,8 +692,28 @@ int msgpack_unserialize_map_item(msgpack_unpack_data *unpack, zval **container,
                         __FUNCTION__, Z_STRVAL_P(key));
 #else
                     ce = msgpack_unserialize_class(container, Z_STR_P(key), 0);
+                    /* Enums are not allowed to implement Serializable nor __unserialize */
+                    if (ce == NULL || ce == PHP_IC_ENTRY) {
+                        MSGPACK_WARNING(
+                            "[msgpack] (%s) Enum definition %s could not be loaded",
+                            __FUNCTION__, Z_STRVAL_P(key));
+
+                        MSGPACK_UNSERIALIZE_FINISH_MAP_ITEM(unpack, key, val);
+                        return 0;
+                    }
+
+                    /* found class is not an Enum but a normal Class */
+                    if (!(ce->ce_flags & ZEND_ACC_ENUM)) {
+                        MSGPACK_WARNING(
+                            "[msgpack] (%s) Class %s is expected to be an Enum",
+                            __FUNCTION__, ZSTR_VAL(ce->name));
+
+                        MSGPACK_UNSERIALIZE_FINISH_MAP_ITEM(unpack, key, val);
+                        return 0;
+                    }
+
                     zend_object *enum_instance = zend_enum_get_case(ce, Z_STR_P(val));
-                    ZVAL_OBJ(*container, enum_instance);
+                    ZVAL_OBJ_COPY(*container, enum_instance);
 #endif
                     MSGPACK_UNSERIALIZE_FINISH_MAP_ITEM(unpack, key, val);
                     return 0;
diff --git a/tests/enum002.phpt b/tests/enum002.phpt
new file mode 100644
index 0000000..56895d7
--- /dev/null
+++ b/tests/enum002.phpt
@@ -0,0 +1,27 @@
+--TEST--
+Enums
+--SKIPIF--
+<?php
+if (!extension_loaded("msgpack")) {
+    exit('skip because msgpack extension is missing');
+}
+if (version_compare(PHP_VERSION, '8.1.0', '<')) {
+    exit('skip Enum tests in PHP older than 8.1.0');
+}
+?>
+--FILE--
+<?php
+$unpacked = msgpack_unpack(file_get_contents(__DIR__."/enum002.ser.txt"));
+var_dump($unpacked);
+?>
+DONE
+--EXPECTF--
+Warning: [msgpack] (msgpack_unserialize_map_item) Enum definition test\TestEnum could not be loaded in %senum002.php on line 2
+array(1) {
+  ["enum"]=>
+  object(__PHP_Incomplete_Class)#1 (1) {
+    ["__PHP_Incomplete_Class_Name"]=>
+    string(13) "test\TestEnum"
+  }
+}
+DONE
diff --git a/tests/enum002.ser.txt b/tests/enum002.ser.txt
new file mode 100644
index 0000000..7229336
--- /dev/null
+++ b/tests/enum002.ser.txt
@@ -0,0 +1 @@
+¤enum‚À­test\TestEnumĦA
\ No newline at end of file
diff --git a/tests/enum003.phpt b/tests/enum003.phpt
new file mode 100644
index 0000000..3ffe176
--- /dev/null
+++ b/tests/enum003.phpt
@@ -0,0 +1,33 @@
+--TEST--
+Enums
+--SKIPIF--
+<?php
+if (!extension_loaded("msgpack")) {
+    exit('skip because msgpack extension is missing');
+}
+if (version_compare(PHP_VERSION, '8.1.0', '<')) {
+    exit('skip Enum tests in PHP older than 8.1.0');
+}
+if (defined("PHP_DEBUG") && PHP_DEBUG) {
+    die('skip debug build');
+}
+?>
+--FILE--
+<?php
+namespace test;
+
+class TestEnum {
+
+}
+
+$unpacked = msgpack_unpack(file_get_contents(__DIR__."/enum002.ser.txt"));
+var_dump($unpacked);
+?>
+DONE
+--EXPECTF--
+Warning: [msgpack] (msgpack_unserialize_map_item) Class test\TestEnum is expected to be an Enum in %senum003.php on line 8
+array(1) {
+  ["enum"]=>
+  NULL
+}
+DONE
diff --git a/tests/issue181.phpt b/tests/issue181.phpt
new file mode 100644
index 0000000..a3d844f
--- /dev/null
+++ b/tests/issue181.phpt
@@ -0,0 +1,43 @@
+--TEST--
+Issue #181 (zend_mm_heap corrupted when serializing/unserializing Enum)
+--SKIPIF--
+<?php
+if (!extension_loaded("msgpack")) {
+    exit('skip because msgpack extension is missing');
+}
+if (version_compare(PHP_VERSION, '8.1.0', '<')) {
+    exit('skip Enum tests in PHP older than 8.1.0');
+}
+?>
+--FILE--
+Test
+<?php
+
+enum TestEnum: string
+{
+    case EITHER = 'either';
+    case OTHER = 'other';
+}
+
+$original = (object)[
+    'either' => TestEnum::EITHER,
+    'other' => TestEnum::OTHER,
+];
+
+for ($i = 0; $i < 10; $i++) {
+    $packed = msgpack_pack($original);
+    $unpacked = msgpack_unpack($packed);
+    if ($unpacked->either !== TestEnum::EITHER) {
+        echo 'either mismatch';
+    }
+    if ($original->other !== TestEnum::OTHER) {
+        echo 'other mismatch';
+    }
+    unset($packed);
+    unset($unpacked);
+}
+?>
+OK
+--EXPECT--
+Test
+OK