diff --git a/ext/spl/spl_heap.c b/ext/spl/spl_heap.c
index 254fbde7b3ff..5d36266393b0 100644
--- a/ext/spl/spl_heap.c
+++ b/ext/spl/spl_heap.c
@@ -1257,6 +1257,10 @@ PHP_METHOD(SplHeap, __unserialize)
 		Z_PARAM_ARRAY_HT(data)
 	ZEND_PARSE_PARAMETERS_END();
 
+	if (UNEXPECTED(spl_heap_consistency_validations(intern, true) != SUCCESS)) {
+		RETURN_THROWS();
+	}
+
 	if (zend_hash_num_elements(data) != 2) {
 		zend_throw_exception_ex(NULL, 0, "Invalid serialization data for %s object", ZSTR_VAL(intern->std.ce->name));
 		RETURN_THROWS();
@@ -1285,10 +1289,6 @@ PHP_METHOD(SplHeap, __unserialize)
 		RETURN_THROWS();
 	}
 
-	if (EG(exception)) {
-		RETURN_THROWS();
-	}
-
 	if (UNEXPECTED(spl_heap_consistency_validations(intern, false) != SUCCESS)) {
 		RETURN_THROWS();
 	}
diff --git a/ext/spl/tests/heap_unserialize_under_corruption_or_modification.phpt b/ext/spl/tests/heap_unserialize_under_corruption_or_modification.phpt
new file mode 100644
index 000000000000..2e54be09ad1a
--- /dev/null
+++ b/ext/spl/tests/heap_unserialize_under_corruption_or_modification.phpt
@@ -0,0 +1,30 @@
+--TEST--
+SplHeap should not accept unserialize data when it is corrupted or under modification
+--FILE--
+<?php
+
+class MyHeap extends SplMaxHeap {
+    public function compare($a, $b): int {
+        global $array;
+        static $counter = 0;
+        if ($counter++ === 0)
+            $this->__unserialize($array);
+        return $a < $b ? -1 : ($a == $b ? 0 : 1);
+    }
+}
+
+$heap = new SplMaxHeap;
+$heap->insert(1);
+$array = $heap->__serialize();
+
+$heap = new MyHeap;
+$heap->insert(0);
+try {
+    $heap->insert(2);
+} catch (RuntimeException $e) {
+    echo $e->getMessage(), "\n";
+}
+
+?>
+--EXPECT--
+Heap cannot be changed when it is already being modified.