diff --git a/VulkanHppGenerator.cpp b/VulkanHppGenerator.cpp
index cc72544..547c8aa 100644
--- a/VulkanHppGenerator.cpp
+++ b/VulkanHppGenerator.cpp
@@ -5682,7 +5682,6 @@ void VulkanHppGenerator::appendStructConstructorsEnhanced( std::string &
         if ( litit != lenIts.end() )
         {
           // len arguments just have an initalizer, from the ArrayProxyNoTemporaries size
-          assert( ( litit->second.size() == 1 ) || !litit->second.front()->optional );
           initializers +=
             ( firstArgument ? ": " : ", " ) + mit->name + "( " + generateLenInitializer( mit, litit ) + " )";
           sizeChecks += generateSizeCheck( litit->second, stripPrefix( structData.first, "Vk" ), prefix );
@@ -7162,16 +7161,16 @@ std::string
           std::string secondName     = startLowerCase( stripPrefix( arrayIts[second]->name, "p" ) ) + "_";
           std::string assertionCheck = firstName + ".size() == " + secondName + ".size()";
           std::string throwCheck     = firstName + ".size() != " + secondName + ".size()";
-          if ( arrayIts[first]->optional || arrayIts[second]->optional )
+          if ( ( !arrayIts[first]->optional.empty() && arrayIts[first]->optional.front() ) || ( !arrayIts[second]->optional.empty() && arrayIts[second]->optional.front() ) )
           {
             assertionCheck = "( " + assertionCheck + " )";
             throwCheck     = "( " + throwCheck + " )";
-            if ( arrayIts[second]->optional )
+            if ( !arrayIts[second]->optional.empty() && arrayIts[second]->optional.front() )
             {
               assertionCheck = secondName + ".empty() || " + assertionCheck;
               throwCheck     = "!" + secondName + ".empty() && " + throwCheck;
             }
-            if ( arrayIts[first]->optional )
+            if ( !arrayIts[first]->optional.empty() && arrayIts[first]->optional.front() )
             {
               assertionCheck = firstName + ".empty() || " + assertionCheck;
               throwCheck     = "!" + firstName + ".empty() && " + throwCheck;
@@ -9288,7 +9287,12 @@ void VulkanHppGenerator::readStructMember( tinyxml2::XMLElement const * element,
     }
     else if ( attribute.first == "optional" )
     {
-      memberData.optional = ( attribute.second == "true" );
+      std::vector<std::string> optional = tokenize( attribute.second, "," );
+      memberData.optional.reserve( optional.size() );
+      for ( auto const & o : optional )
+      {
+        memberData.optional.push_back( o == "true" );
+      }
     }
     else if ( attribute.first == "selection" )
     {
diff --git a/VulkanHppGenerator.hpp b/VulkanHppGenerator.hpp
index ed4ebbe..c757be6 100644
--- a/VulkanHppGenerator.hpp
+++ b/VulkanHppGenerator.hpp
@@ -222,7 +222,7 @@ private:
     std::string              bitCount;
     std::vector<std::string> len;
     bool                     noAutoValidity = false;
-    bool                     optional       = false;
+    std::vector<bool>        optional;
     std::string              selection;
     std::string              selector;
     std::vector<std::string> values;
diff --git a/vulkan/vulkan.hpp b/vulkan/vulkan.hpp
index 54d4e25..a0081ec 100644
--- a/vulkan/vulkan.hpp
+++ b/vulkan/vulkan.hpp
@@ -17850,13 +17850,13 @@ namespace VULKAN_HPP_NAMESPACE
       , scratchData( scratchData_ )
     {
 #    ifdef VULKAN_HPP_NO_EXCEPTIONS
-      VULKAN_HPP_ASSERT( geometries_.size() == pGeometries_.size() );
+      VULKAN_HPP_ASSERT( geometries_.empty() || pGeometries_.empty() || ( geometries_.size() == pGeometries_.size() ) );
 #    else
-      if ( geometries_.size() != pGeometries_.size() )
+      if ( !geometries_.empty() && !pGeometries_.empty() && ( geometries_.size() != pGeometries_.size() ) )
       {
         throw LogicError(
           VULKAN_HPP_NAMESPACE_STRING
-          "::AccelerationStructureBuildGeometryInfoKHR::AccelerationStructureBuildGeometryInfoKHR: geometries_.size() != pGeometries_.size()" );
+          "::AccelerationStructureBuildGeometryInfoKHR::AccelerationStructureBuildGeometryInfoKHR: !geometries_.empty() && !pGeometries_.empty() && ( geometries_.size() != pGeometries_.size() )" );
       }
 #    endif /*VULKAN_HPP_NO_EXCEPTIONS*/
     }