diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpNextgenClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpNextgenClientCodegen.java
index 1c0e077a0f0a..3c57a89f4abf 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpNextgenClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/PhpNextgenClientCodegen.java
@@ -149,7 +149,7 @@ public class PhpNextgenClientCodegen extends AbstractPhpCodegen {
                     propType = prop.dataType;
                 }
 
-                if ((!prop.required || prop.isNullable) && propType != "mixed") { // optional or nullable but not mixed
+                if ((!prop.required || prop.isNullable) && !propType.equals("mixed")) { // optional or nullable but not mixed
                     propType = "?" + propType;
                 }