diff --git a/VulkanHppGenerator.cpp b/VulkanHppGenerator.cpp
index 9ef939d..f949e6e 100644
--- a/VulkanHppGenerator.cpp
+++ b/VulkanHppGenerator.cpp
@@ -144,6 +144,8 @@ void VulkanHppGenerator::generateEnumsHppFile() const
 // include-what-you-use: make sure, vulkan.hpp is used by code-completers
 // IWYU pragma: private; include "vulkan.hpp"
 
+#include <type_traits>    // for std::underlying_type
+
 namespace VULKAN_HPP_NAMESPACE
 {
 ${Flags}
diff --git a/vulkan/vulkan_enums.hpp b/vulkan/vulkan_enums.hpp
index 06e0cbf..fa22c01 100644
--- a/vulkan/vulkan_enums.hpp
+++ b/vulkan/vulkan_enums.hpp
@@ -11,6 +11,8 @@
 // include-what-you-use: make sure, vulkan.hpp is used by code-completers
 // IWYU pragma: private; include "vulkan.hpp"
 
+#include <type_traits>  // for std::underlying_type
+
 namespace VULKAN_HPP_NAMESPACE
 {
   template <typename FlagBitsType>