diff --git a/Source/HoudiniEngineEditor/Private/HoudiniEngineEditorPrivatePCH.h b/Source/HoudiniEngineEditor/Private/HoudiniEngineEditorPrivatePCH.h
index 16a27b5..9376c23 100644
--- a/Source/HoudiniEngineEditor/Private/HoudiniEngineEditorPrivatePCH.h
+++ b/Source/HoudiniEngineEditor/Private/HoudiniEngineEditorPrivatePCH.h
@@ -40,6 +40,7 @@
 
 
 #define HOUDINI_PARAMETER_STRING_REF_TAG						TEXT("unreal_ref")
+#define HOUDINI_PARAMETER_STRING_REF_CLASS_TAG                  TEXT("unreal_ref_class")
 #define HOUDINI_PARAMETER_STRING_MULTILINE_TAG					TEXT("editor")
 
  // URL used for bug reporting.
diff --git a/Source/HoudiniEngineEditor/Private/HoudiniParameterDetails.cpp b/Source/HoudiniEngineEditor/Private/HoudiniParameterDetails.cpp
index c67bff3..d49c479 100644
--- a/Source/HoudiniEngineEditor/Private/HoudiniParameterDetails.cpp
+++ b/Source/HoudiniEngineEditor/Private/HoudiniParameterDetails.cpp
@@ -2105,6 +2105,7 @@ FHoudiniParameterDetails::CreateWidgetString( IDetailCategoryBuilder & HouParame
 
 	bool bIsMultiLine = false;
 	bool bIsUnrealRef = false;
+	UClass* UnrealRefClass = UObject::StaticClass();
 
 	// Create the standard parameter name widget.
 	CreateNameWidget(Row, InParams, true);
@@ -2114,6 +2115,15 @@ FHoudiniParameterDetails::CreateWidgetString( IDetailCategoryBuilder & HouParame
 	if (Tags.Contains(HOUDINI_PARAMETER_STRING_REF_TAG) && FCString::Atoi(*Tags[HOUDINI_PARAMETER_STRING_REF_TAG]) == 1) 
 	{
 		bIsUnrealRef = true;
+
+		if (Tags.Contains(HOUDINI_PARAMETER_STRING_REF_CLASS_TAG))
+		{
+			UClass* FoundClass = FindObject<UClass>(ANY_PACKAGE, *Tags[HOUDINI_PARAMETER_STRING_REF_CLASS_TAG]);
+			if (FoundClass != nullptr)
+			{
+				UnrealRefClass = FoundClass;
+			}
+		}
 	}
 
 	if (Tags.Contains(HOUDINI_PARAMETER_STRING_MULTILINE_TAG)) 
@@ -2179,8 +2189,10 @@ FHoudiniParameterDetails::CreateWidgetString( IDetailCategoryBuilder & HouParame
 			VerticalBox->AddSlot().Padding(2, 2, 5, 2)
 			[
 				SNew(SAssetDropTarget)
-				.OnIsAssetAcceptableForDrop_Lambda([](const UObject* InObject)
-					{return true; })
+				.OnIsAssetAcceptableForDrop_Lambda([=](const UObject* InObject)
+				{
+					return InObject->IsA(UnrealRefClass);
+				})
 				.OnAssetDropped_Lambda([=](UObject* InObject)
 				{
 					// Get the asset reference string for this object
@@ -2266,10 +2278,10 @@ FHoudiniParameterDetails::CreateWidgetString( IDetailCategoryBuilder & HouParame
 				]
 			];
 			
-			StaticMeshComboButton->SetOnGetMenuContent(FOnGetContent::CreateLambda([StaticMeshComboButton, ChangeStringValueAt, Idx, StringParams]()
+			StaticMeshComboButton->SetOnGetMenuContent(FOnGetContent::CreateLambda([UnrealRefClass, StaticMeshComboButton, ChangeStringValueAt, Idx, StringParams]()
 			{
 				TArray<const UClass *> AllowedClasses;
-				AllowedClasses.Add(UObject::StaticClass());
+				AllowedClasses.Add(UnrealRefClass);
 				TArray< UFactory * > NewAssetFactories;
 				return PropertyCustomizationHelpers::MakeAssetPickerWithMenu(
 					FAssetData(nullptr),