diff --git a/DataFormats/PortableTestObjects/src/classes_def.xml b/DataFormats/PortableTestObjects/src/classes_def.xml
index caafb7f08ea21..6a57029fdcbd1 100644
--- a/DataFormats/PortableTestObjects/src/classes_def.xml
+++ b/DataFormats/PortableTestObjects/src/classes_def.xml
@@ -1,15 +1,29 @@
 <lcgdict>
   <class name="portabletest::TestHostCollection"/>
+  <!-- portabletest::TestHostCollection::Layout alias must be listed before the aliased-to type -->
+  <class name="portabletest::TestHostCollection::Layout"/>
   <class name="edm::Wrapper<portabletest::TestHostCollection>" splitLevel="0"/>
 
-  <class name="portabletest::TestStruct"/>
   <class name="portabletest::TestHostObject"/>
+  <!-- portabletest::TestHostObject::Product alias must be listed before the aliased-to type -->
+  <class name="portabletest::TestHostObject::Product"/>
   <class name="edm::Wrapper<portabletest::TestHostObject>"/>
+  <class name="portabletest::TestStruct"/>
 
   <class name="portabletest::TestSoALayout<128,false>"/>
   <class name="portabletest::TestSoALayout2<128,false>"/>
   <class name="portabletest::TestSoALayout3<128,false>"/>
 
+  <!-- Collection declaration for dictionary -->
+  <class name="portabletest::TestHostMultiCollection2"/>
+  <!-- portabletest::TestHostObject::Implementation alias must be listed before the aliased-to type -->
+  <class name="portabletest::TestHostMultiCollection2::Implementation"/>
+
+  <!-- Collection declaration for dictionary -->
+  <class name="portabletest::TestHostMultiCollection3"/>
+  <!-- portabletest::TestHostObject::Implementation alias must be listed before the aliased-to type -->
+  <class name="portabletest::TestHostMultiCollection3::Implementation"/>
+
   <!-- Recursive templates (with no data) ensuring we have one CollectionLeaf<index, type> for each layout in the collection -->
   <class name="portablecollection::CollectionImpl<0, portabletest::TestSoALayout<128, false>, portabletest::TestSoALayout2<128, false>>"/>
   <class name="portablecollection::CollectionImpl<1, portabletest::TestSoALayout2<128, false>>"/>
@@ -18,9 +32,6 @@
   <class name="portablecollection::CollectionLeaf<0, portabletest::TestSoALayout<128, false>>"/>
   <class name="portablecollection::CollectionLeaf<1, portabletest::TestSoALayout2<128, false>>"/>
 
-  <!-- Collection declaration for dictionary -->
-  <class name="portabletest::TestHostMultiCollection2"/>
-
   <class name="edm::Wrapper<portabletest::TestHostMultiCollection2>" splitLevel="0"/>
 
   <!-- Recursive templates (with no data) ensuring we have one CollectionLeaf<index, type> for each layout in the collection -->
@@ -35,9 +46,6 @@
   -->
   <class name="portablecollection::CollectionLeaf<2, portabletest::TestSoALayout3<128, false>>"/>
 
-  <!-- Collection declaration for dictionary -->
-  <class name="portabletest::TestHostMultiCollection3"/>
-
   <class name="edm::Wrapper<portabletest::TestHostMultiCollection3>" splitLevel="0"/>
 
   <class name="portabletest::TestProductWithPtr<alpaka_common::DevHost>"/>