diff --git a/Vulkan-Docs b/Vulkan-Docs
index 4ad4fd1..8cc971f 160000
--- a/Vulkan-Docs
+++ b/Vulkan-Docs
@@ -1 +1 @@
-Subproject commit 4ad4fd17161efd9bfd1125c0c9d17db6fb276216
+Subproject commit 8cc971fb3e1c25afb949cdc49d6a6de63f19c5c6
diff --git a/VulkanHppGenerator.cpp b/VulkanHppGenerator.cpp
index de14a2f..28799d3 100644
--- a/VulkanHppGenerator.cpp
+++ b/VulkanHppGenerator.cpp
@@ -758,6 +758,13 @@ std::pair<bool, std::string> writeFunctionBodyStandardReturn(std::string const&
   return std::make_pair(castReturn, ret);
 }
 
+VulkanHppGenerator::VulkanHppGenerator()
+{
+  m_handles.insert(std::make_pair("", HandleData()));   // insert the default "handle" without class (for createInstance, and such)
+#if !defined(NDEBUG)
+#endif
+}
+
 bool VulkanHppGenerator::containsUnion(std::string const& type) const
 {
   // a simple recursive check if a type is or contains a union
@@ -826,13 +833,7 @@ std::string VulkanHppGenerator::defaultValue(std::string const& type) const
   }
   else
   {
-#if !defined(NDEBUG)
-    static const std::set<std::string> otherTypes =
-    {
-      "DWORD", "float", "HANDLE", "HINSTANCE", "HWND", "int", "int32_t", "size_t", "uint32_t", "uint64_t", "uint8_t", "Window", "xcb_window_t", "zx_handle_t"
-    };
-    assert(otherTypes.find(type) != otherTypes.end());
-#endif
+    assert(m_defaultZeroTypes.find(type) != m_defaultZeroTypes.end());
     return "0";
   }
 }
@@ -1817,6 +1818,19 @@ void VulkanHppGenerator::readRequireEnum(tinyxml2::XMLElement const* element, st
   }
 }
 
+#if !defined(NDEBUG)
+void VulkanHppGenerator::readRequires(tinyxml2::XMLElement const* element, std::map<std::string, std::string> const& attributes)
+{
+  checkAttributes(attributes, element->GetLineNum(), { {"name", {}}, { "requires", {}} }, {});
+  checkElements(getChildElements(element), {});
+
+  auto nameIt = attributes.find("name");
+  assert(nameIt != attributes.end());
+  assert(m_defaultZeroTypes.find(nameIt->second) == m_defaultZeroTypes.end());
+  m_defaultZeroTypes.insert(nameIt->second);
+}
+#endif
+
 void VulkanHppGenerator::readStruct(tinyxml2::XMLElement const* element, bool isUnion, std::map<std::string, std::string> const& attributes)
 {
   checkAttributes(attributes, element->GetLineNum(),
@@ -2016,10 +2030,21 @@ void VulkanHppGenerator::readType(tinyxml2::XMLElement const* element)
       throw std::runtime_error("Spec error on line " + lineNumber + ": unknown category <" + categoryIt->second + ">");
     }
   }
+#if !defined(NDEBUG)
   else
   {
-    assert(attributes.find("name") != attributes.end());
+    auto requiresIt = attributes.find("requires");
+    if (requiresIt != attributes.end())
+    {
+      readRequires(element, attributes);
+    }
+    else
+    {
+      assert((attributes.size() == 1) && (attributes.begin()->first == "name") && (attributes.begin()->second == "int"));
+      m_defaultZeroTypes.insert("int");
+    }
   }
+#endif
 }
 
 void VulkanHppGenerator::readTypes(tinyxml2::XMLElement const* element)
diff --git a/VulkanHppGenerator.hpp b/VulkanHppGenerator.hpp
index 616cb98..430b667 100644
--- a/VulkanHppGenerator.hpp
+++ b/VulkanHppGenerator.hpp
@@ -23,10 +23,7 @@
 class VulkanHppGenerator
 {
   public:
-    VulkanHppGenerator()
-    {
-      m_handles.insert(std::make_pair("", HandleData()));   // insert the default "handle" without class (for createInstance, and such)
-    }
+    VulkanHppGenerator();
 
     void checkCorrectness();
     std::string const& getTypesafeCheck() const;
@@ -222,6 +219,9 @@ class VulkanHppGenerator
     void writeStructure(std::ostream & os, std::pair<std::string, StructureData> const& structure) const;
     void writeUnion(std::ostream & os, std::pair<std::string, StructureData> const& structure) const;
     void writeUniqueTypes(std::ostream &os, std::string const& parentType, std::set<std::string> const& childrenTypes) const;
+#if !defined(NDEBUG)
+    void readRequires(tinyxml2::XMLElement const* element, std::map<std::string, std::string> const& attributes);
+#endif
 
   private:
     std::map<std::string, std::string>    m_baseTypes;
@@ -239,6 +239,7 @@ class VulkanHppGenerator
     std::string                           m_version;
     std::string                           m_vulkanLicenseHeader;
 #if !defined(NDEBUG)
+    std::set<std::string>                 m_defaultZeroTypes;
     std::set<std::string>                 m_defines;        // just used for verfication in readExtensionType
 #endif
 };