diff --git a/NEWS b/NEWS
index c3df7be79eb..0a268eb4995 100644
--- a/NEWS
+++ b/NEWS
@@ -39,6 +39,10 @@ PHP                                                                        NEWS
   . Fixed bug GH-13519 (PGSQL_CONNECT_FORCE_RENEW not working with persistent
     connections. (David Carlier)
 
+- SPL:
+  . Fixed bug GH-13531 (Unable to resize SplfixedArray after being unserialized
+    in PHP 8.2.15). (nielsdos)
+
 - Standard:
   . Fixed bug GH-13279 (Instable array during in-place modification in uksort).
     (ilutov)
diff --git a/ext/spl/spl_fixedarray.c b/ext/spl/spl_fixedarray.c
index 95ab191b778..14be941cd33 100644
--- a/ext/spl/spl_fixedarray.c
+++ b/ext/spl/spl_fixedarray.c
@@ -89,6 +89,7 @@ static void spl_fixedarray_default_ctor(spl_fixedarray *array)
 {
 	array->size = 0;
 	array->elements = NULL;
+	array->cached_resize = -1;
 }
 
 /* Initializes the range [from, to) to null. Does not dtor existing elements. */
@@ -107,6 +108,7 @@ static void spl_fixedarray_init_non_empty_struct(spl_fixedarray *array, zend_lon
 	array->size = 0; /* reset size in case ecalloc() fails */
 	array->elements = size ? safe_emalloc(size, sizeof(zval), 0) : NULL;
 	array->size = size;
+	array->cached_resize = -1;
 }
 
 static void spl_fixedarray_init(spl_fixedarray *array, zend_long size)
@@ -117,7 +119,6 @@ static void spl_fixedarray_init(spl_fixedarray *array, zend_long size)
 	} else {
 		spl_fixedarray_default_ctor(array);
 	}
-	array->cached_resize = -1;
 }
 
 /* Copies the range [begin, end) into the fixedarray, beginning at `offset`.
diff --git a/ext/spl/tests/gh13531.phpt b/ext/spl/tests/gh13531.phpt
new file mode 100644
index 00000000000..46503ccf22a
--- /dev/null
+++ b/ext/spl/tests/gh13531.phpt
@@ -0,0 +1,28 @@
+--TEST--
+GH-13531 (Unable to resize SplfixedArray after being unserialized in PHP 8.2.15)
+--FILE--
+<?php
+
+$array = new SplFixedArray(5);
+$array[4] = 1;
+$serialized = serialize($array);
+$unserialized = unserialize($serialized);
+$unserialized->setSize(6);
+var_dump($unserialized);
+
+?>
+--EXPECT--
+object(SplFixedArray)#2 (6) {
+  [0]=>
+  NULL
+  [1]=>
+  NULL
+  [2]=>
+  NULL
+  [3]=>
+  NULL
+  [4]=>
+  int(1)
+  [5]=>
+  NULL
+}