diff --git a/UPGRADING.md b/UPGRADING.md
index 6c830703..828d7335 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -45,6 +45,9 @@ Regenerate classes:
 ./vendor/bin/soap-client generate:clientfactory --config=config/soap-client.php
 ```
 
+**Note:** The generated code might have slightly changed for your project.
+Validate if you are still using the correct methods in your implementation.
+
 Change the engine inside your (generated) ClientFactory:
 
 ```php
diff --git a/spec/Phpro/SoapClient/CodeGenerator/Util/NormalizerSpec.php b/spec/Phpro/SoapClient/CodeGenerator/Util/NormalizerSpec.php
index 36721c76..666e1822 100644
--- a/spec/Phpro/SoapClient/CodeGenerator/Util/NormalizerSpec.php
+++ b/spec/Phpro/SoapClient/CodeGenerator/Util/NormalizerSpec.php
@@ -81,11 +81,11 @@ function it_generates_property_methods()
     {
         $this->generatePropertyMethod('get', 'prop1')->shouldReturn('getProp1');
         $this->generatePropertyMethod('set', 'prop1')->shouldReturn('setProp1');
-        $this->generatePropertyMethod('get', 'prop1_test*./')->shouldReturn('getProp1Test');
+        $this->generatePropertyMethod('get', 'prop1_test*./')->shouldReturn('getProp1_test');
         $this->generatePropertyMethod('get', 'UpperCased')->shouldReturn('getUpperCased');
-        $this->generatePropertyMethod('get', 'my-./*prop_123')->shouldReturn('getMyProp123');
-        $this->generatePropertyMethod('get', 'My-./*prop_123')->shouldReturn('getMyProp123');
-        $this->generatePropertyMethod('get', 'My-./final*prop_123')->shouldReturn('getMyFinalProp123');
+        $this->generatePropertyMethod('get', 'my-./*prop_123')->shouldReturn('getMyProp_123');
+        $this->generatePropertyMethod('get', 'My-./*prop_123')->shouldReturn('getMyProp_123');
+        $this->generatePropertyMethod('get', 'My-./final*prop_123')->shouldReturn('getMyFinalProp_123');
         $this->generatePropertyMethod('get', 'final')->shouldReturn('getFinal');
         $this->generatePropertyMethod('set', 'Final')->shouldReturn('setFinal');
         $this->generatePropertyMethod('set', '_')->shouldReturn('set_');
diff --git a/src/Phpro/SoapClient/CodeGenerator/Util/Normalizer.php b/src/Phpro/SoapClient/CodeGenerator/Util/Normalizer.php
index 2d642c65..ef2e90f7 100644
--- a/src/Phpro/SoapClient/CodeGenerator/Util/Normalizer.php
+++ b/src/Phpro/SoapClient/CodeGenerator/Util/Normalizer.php
@@ -234,7 +234,7 @@ public static function isKnownType(string $type): bool
      */
     public static function generatePropertyMethod(string $prefix, string $property): string
     {
-        $normalized = $property === '_' ? $property : self::camelCase($property, '{[^a-z0-9]+}i');
+        $normalized = $property === '_' ? $property : self::camelCase($property, '{[^a-z0-9_]+}i');
 
         return strtolower($prefix).ucfirst($normalized);
     }