diff --git a/NEWS b/NEWS
index 50c3346e17a3..41ee6be929d6 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,8 @@ PHP                                                                        NEWS
     100-continue flow control). (Sjoerd Langkemper)
 
 - Intl:
+  . Fixed a memory leak when iterating IntlBreakIterator::getPartsIterator()
+    results. (iliaal)
   . Fixed a leak in Locale::getKeywords() when a keyword value cannot be
     read. (iliaal)
 
diff --git a/Zend/zend_alloc.c b/Zend/zend_alloc.c
index fc7bc1f4d9d4..575b54b11a24 100644
--- a/Zend/zend_alloc.c
+++ b/Zend/zend_alloc.c
@@ -1527,9 +1527,11 @@ static zend_always_inline void zend_mm_free_heap(zend_mm_heap *heap, void *ptr Z
 		ZEND_MM_CHECK(chunk->heap == heap, "zend_mm_heap corrupted");
 		if (EXPECTED(info & ZEND_MM_IS_SRUN)) {
 			zend_mm_free_small(heap, ptr, ZEND_MM_SRUN_BIN_NUM(info));
-		} else /* if (info & ZEND_MM_IS_LRUN) */ {
-			int pages_count = ZEND_MM_LRUN_PAGES(info);
+		} else {
+			/* A freed large run has a zeroed map entry, so this also rejects double frees. */
+			ZEND_MM_CHECK(info & ZEND_MM_IS_LRUN, "zend_mm_heap corrupted");
 
+			int pages_count = ZEND_MM_LRUN_PAGES(info);
 			ZEND_MM_CHECK(ZEND_MM_ALIGNED_OFFSET(page_offset, ZEND_MM_PAGE_SIZE) == 0, "zend_mm_heap corrupted");
 			zend_mm_free_large(heap, chunk, page_num, pages_count);
 		}
@@ -1557,7 +1559,8 @@ static size_t zend_mm_size(zend_mm_heap *heap, void *ptr ZEND_FILE_LINE_DC ZEND_
 		ZEND_MM_CHECK(chunk->heap == heap, "zend_mm_heap corrupted");
 		if (EXPECTED(info & ZEND_MM_IS_SRUN)) {
 			return bin_data_size[ZEND_MM_SRUN_BIN_NUM(info)];
-		} else /* if (info & ZEND_MM_IS_LARGE_RUN) */ {
+		} else {
+			ZEND_MM_CHECK(info & ZEND_MM_IS_LRUN, "zend_mm_heap corrupted");
 			return ZEND_MM_LRUN_PAGES(info) * ZEND_MM_PAGE_SIZE;
 		}
 #endif
@@ -1752,7 +1755,8 @@ static zend_always_inline void *zend_mm_realloc_heap(zend_mm_heap *heap, void *p
 				return ret;
 			}  while (0);
 
-		} else /* if (info & ZEND_MM_IS_LARGE_RUN) */ {
+		} else {
+			ZEND_MM_CHECK(info & ZEND_MM_IS_LRUN, "zend_mm_heap corrupted");
 			ZEND_MM_CHECK(ZEND_MM_ALIGNED_OFFSET(page_offset, ZEND_MM_PAGE_SIZE) == 0, "zend_mm_heap corrupted");
 			old_size = ZEND_MM_LRUN_PAGES(info) * ZEND_MM_PAGE_SIZE;
 			if (size > ZEND_MM_MAX_SMALL_SIZE && size <= ZEND_MM_MAX_LARGE_SIZE) {
diff --git a/ext/intl/breakiterator/breakiterator_iterators.cpp b/ext/intl/breakiterator/breakiterator_iterators.cpp
index d792a6367139..def0fa9d9fc5 100644
--- a/ext/intl/breakiterator/breakiterator_iterators.cpp
+++ b/ext/intl/breakiterator/breakiterator_iterators.cpp
@@ -242,7 +242,7 @@ void IntlIterator_from_BreakIterator_parts(zval *break_iter_zv,
 	ii->iterator->index = 0;
 
 	((zoi_with_current*)ii->iterator)->destroy_it = _breakiterator_parts_destroy_it;
-	ZVAL_OBJ_COPY(&((zoi_with_current*)ii->iterator)->wrapping_obj, Z_OBJ_P(object));
+	ZVAL_UNDEF(&((zoi_with_current*)ii->iterator)->wrapping_obj);
 	ZVAL_UNDEF(&((zoi_with_current*)ii->iterator)->current);
 
 	((zoi_break_iter_parts*)ii->iterator)->bio = Z_INTL_BREAKITERATOR_P(break_iter_zv);
diff --git a/ext/intl/common/common_enum.cpp b/ext/intl/common/common_enum.cpp
index 4260e3cce57f..16c892074915 100644
--- a/ext/intl/common/common_enum.cpp
+++ b/ext/intl/common/common_enum.cpp
@@ -39,6 +39,8 @@ zend_object_handlers IntlIterator_handlers;
 void zoi_with_current_dtor(zend_object_iterator *iter)
 {
 	zoi_with_current *zoiwc = (zoi_with_current*)iter;
+	iter->funcs->invalidate_current(iter);
+	zoiwc->destroy_it(iter);
 	zval_ptr_dtor(&zoiwc->wrapping_obj);
 	ZVAL_UNDEF(&zoiwc->wrapping_obj);
 }
@@ -149,7 +151,6 @@ static void IntlIterator_objects_dtor(zend_object *object)
 {
 	IntlIterator_object	*ii = php_intl_iterator_fetch_object(object);
 	if (ii->iterator) {
-		((zoi_with_current*)ii->iterator)->destroy_it(ii->iterator);
 		OBJ_RELEASE(&ii->iterator->std);
 		ii->iterator = NULL;
 	}
diff --git a/ext/intl/tests/breakiter_parts_iterator_current_leak.phpt b/ext/intl/tests/breakiter_parts_iterator_current_leak.phpt
new file mode 100644
index 000000000000..a006d7f2f792
--- /dev/null
+++ b/ext/intl/tests/breakiter_parts_iterator_current_leak.phpt
@@ -0,0 +1,31 @@
+--TEST--
+IntlPartsIterator must not leak, and a temporary one must not dangle
+--EXTENSIONS--
+intl
+--FILE--
+<?php
+function parts(): IntlPartsIterator {
+    $bi = IntlBreakIterator::createWordInstance('en');
+    $bi->setText('hello world');
+    return $bi->getPartsIterator();
+}
+
+foreach (parts() as $part) {
+    echo "[$part]\n";
+}
+
+$bi = IntlBreakIterator::createWordInstance('en');
+$bi->setText('hello world foo bar baz');
+$m0 = memory_get_usage();
+for ($i = 0; $i < 20000; $i++) {
+    foreach ($bi->getPartsIterator() as $v) {
+        break;
+    }
+}
+var_dump(memory_get_usage() - $m0 < 1024 * 1024);
+?>
+--EXPECT--
+[hello]
+[ ]
+[world]
+bool(true)