diff -Naur a/sapi/fpm/fpm/fpm_main.c b/sapi/fpm/fpm/fpm_main.c
--- a/sapi/fpm/fpm/fpm_main.c	2023-09-15 10:35:39.251222023 +0200
+++ b/sapi/fpm/fpm/fpm_main.c	2023-09-15 10:36:26.554848475 +0200
@@ -1388,7 +1388,6 @@
 	int *mode = (int *)arg;
 	char *key;
 	char *value = NULL;
-	struct key_value_s kv;
 
 	if (!mode || !arg1) return;
 
@@ -1399,7 +1398,7 @@
 
 	key = Z_STRVAL_P(arg1);
 
-	if (!key || strlen(key) < 1) {
+	if (!key || Z_STRLEN_P(arg1) < 1) {
 		zlog(ZLOG_ERROR, "Passing INI directive through FastCGI: empty key");
 		return;
 	}
@@ -1413,10 +1412,8 @@
 		return;
 	}
 
-	kv.key = key;
-	kv.value = value;
-	kv.next = NULL;
-	if (fpm_php_apply_defines_ex(&kv, *mode) == -1) {
+	// zend_string of arg2 is marked persistent but releasing doesn't know. so pass the internal char*
+	if (zend_alter_ini_entry_chars(Z_STR_P(arg1), value, Z_STRLEN_P(arg2), *mode, PHP_INI_STAGE_HTACCESS) == FAILURE) {
 		zlog(ZLOG_ERROR, "Passing INI directive through FastCGI: unable to set '%s'", key);
 	}
 }