diff --git a/modules/openapi-generator/src/main/resources/php-nextgen/ObjectSerializer.mustache b/modules/openapi-generator/src/main/resources/php-nextgen/ObjectSerializer.mustache
index 31649766e30..1e3d5027110 100644
--- a/modules/openapi-generator/src/main/resources/php-nextgen/ObjectSerializer.mustache
+++ b/modules/openapi-generator/src/main/resources/php-nextgen/ObjectSerializer.mustache
@@ -83,7 +83,7 @@ class ObjectSerializer
                     $getter = $data::getters()[$property];
                     $value = $data->$getter();
                     if ($value !== null && !in_array($openAPIType, [{{&primitives}}], true)) {
-                        if (is_sublass_of($openAPIType, '\BackedEnum')) {
+                        if (is_subclass_of($openAPIType, '\BackedEnum')) {
                             $data = $openAPIType::tryFrom($data);
                             if ($data === null) {
                                 $imploded = implode("', '", array_map(fn($case) => $case->value, $openAPIType::cases()));
diff --git a/samples/client/echo_api/php-nextgen/src/ObjectSerializer.php b/samples/client/echo_api/php-nextgen/src/ObjectSerializer.php
index 0ce7e928bb6..06314dec577 100644
--- a/samples/client/echo_api/php-nextgen/src/ObjectSerializer.php
+++ b/samples/client/echo_api/php-nextgen/src/ObjectSerializer.php
@@ -93,7 +93,7 @@ class ObjectSerializer
                     $getter = $data::getters()[$property];
                     $value = $data->$getter();
                     if ($value !== null && !in_array($openAPIType, ['\DateTime', '\SplFileObject', 'array', 'bool', 'boolean', 'byte', 'float', 'int', 'integer', 'mixed', 'number', 'object', 'string', 'void'], true)) {
-                        if (is_sublass_of($openAPIType, '\BackedEnum')) {
+                        if (is_subclass_of($openAPIType, '\BackedEnum')) {
                             $data = $openAPIType::tryFrom($data);
                             if ($data === null) {
                                 $imploded = implode("', '", array_map(fn($case) => $case->value, $openAPIType::cases()));
diff --git a/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ObjectSerializer.php b/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ObjectSerializer.php
index 4da34a502aa..afee7e684f2 100644
--- a/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ObjectSerializer.php
+++ b/samples/client/petstore/php-nextgen/OpenAPIClient-php/src/ObjectSerializer.php
@@ -92,7 +92,7 @@ class ObjectSerializer
                     $getter = $data::getters()[$property];
                     $value = $data->$getter();
                     if ($value !== null && !in_array($openAPIType, ['\DateTime', '\SplFileObject', 'array', 'bool', 'boolean', 'byte', 'float', 'int', 'integer', 'mixed', 'number', 'object', 'string', 'void'], true)) {
-                        if (is_sublass_of($openAPIType, '\BackedEnum')) {
+                        if (is_subclass_of($openAPIType, '\BackedEnum')) {
                             $data = $openAPIType::tryFrom($data);
                             if ($data === null) {
                                 $imploded = implode("', '", array_map(fn($case) => $case->value, $openAPIType::cases()));