diff --git a/processor/pom.xml b/processor/pom.xml
index b3f06dfa..5a741268 100644
--- a/processor/pom.xml
+++ b/processor/pom.xml
@@ -54,7 +54,7 @@
     
     <!-- Dependency Versions -->
     <auto-service.version>1.1.1</auto-service.version>
-    <javapoet.version>0.8.0</javapoet.version>
+    <javapoet.version>0.9.0</javapoet.version>
     <commons-lang.version>3.20.0</commons-lang.version>
     <commons-collections.version>4.5.0</commons-collections.version>
     <junit-jupiter.version>6.0.1</junit-jupiter.version>
diff --git a/processor/src/main/java/org/javahelpers/simple/builders/processor/util/JavapoetMapper.java b/processor/src/main/java/org/javahelpers/simple/builders/processor/util/JavapoetMapper.java
index 7a407497..bdc986bd 100644
--- a/processor/src/main/java/org/javahelpers/simple/builders/processor/util/JavapoetMapper.java
+++ b/processor/src/main/java/org/javahelpers/simple/builders/processor/util/JavapoetMapper.java
@@ -77,11 +77,9 @@ public static TypeName map2ParameterType(
         instanceof org.javahelpers.simple.builders.processor.dtos.TypeNameVariable typeVariable) {
       return TypeVariableName.get(typeVariable.getClassName());
     }
-    ClassName classNameParameter =
-        ClassName.get(parameterType.getPackageName(), parameterType.getClassName());
-    if (parameterType instanceof TypeNameArray parameterTypeArray) {
-      return ArrayTypeName.of(map2ParameterType(parameterTypeArray.getTypeOfArray()));
-    } else if (parameterType instanceof TypeNamePrimitive parameterTypePrim) {
+    // Handle primitives BEFORE calling ClassName.get() to avoid IllegalArgumentException in
+    // JavaPoet 0.9.0+
+    if (parameterType instanceof TypeNamePrimitive parameterTypePrim) {
       return switch (parameterTypePrim.getType()) {
         case BOOLEAN -> TypeName.BOOLEAN;
         case BYTE -> TypeName.BYTE;
@@ -93,7 +91,14 @@ public static TypeName map2ParameterType(
         case SHORT -> TypeName.SHORT;
         default -> null;
       };
-    } else if (parameterType instanceof TypeNameGeneric param) {
+    }
+    if (parameterType instanceof TypeNameArray parameterTypeArray) {
+      return ArrayTypeName.of(map2ParameterType(parameterTypeArray.getTypeOfArray()));
+    }
+    // Now safe to call ClassName.get() for non-primitive types
+    ClassName classNameParameter =
+        ClassName.get(parameterType.getPackageName(), parameterType.getClassName());
+    if (parameterType instanceof TypeNameGeneric param) {
       // Handle raw types (e.g., List without <T>) - return just the class name
       if (param.getInnerTypeArguments().isEmpty()) {
         return classNameParameter;