diff --git a/snippets/macros.hpp b/snippets/macros.hpp
index 9f10f56..55380eb 100644
--- a/snippets/macros.hpp
+++ b/snippets/macros.hpp
@@ -18,6 +18,13 @@
 #  error "${vulkan_hpp} needs at least c++ standard version 11"
 #endif
 
+// include headers holding feature-test macros
+#if 20 <= VULKAN_HPP_CPP_VERSION
+#  include <version>
+#else
+#  include <ciso646>
+#endif
+
 #if defined( VULKAN_HPP_DISABLE_ENHANCED_MODE )
 #  if !defined( VULKAN_HPP_NO_SMART_HANDLE )
 #    define VULKAN_HPP_NO_SMART_HANDLE
diff --git a/vulkan/vulkan_hpp_macros.hpp b/vulkan/vulkan_hpp_macros.hpp
index 583ecfe..9526a76 100644
--- a/vulkan/vulkan_hpp_macros.hpp
+++ b/vulkan/vulkan_hpp_macros.hpp
@@ -28,6 +28,13 @@
 #  error "vulkan.hpp needs at least c++ standard version 11"
 #endif
 
+// include headers holding feature-test macros
+#if 20 <= VULKAN_HPP_CPP_VERSION
+#  include <version>
+#else
+#  include <ciso646>
+#endif
+
 #if defined( VULKAN_HPP_DISABLE_ENHANCED_MODE )
 #  if !defined( VULKAN_HPP_NO_SMART_HANDLE )
 #    define VULKAN_HPP_NO_SMART_HANDLE
diff --git a/vulkan/vulkansc_hpp_macros.hpp b/vulkan/vulkansc_hpp_macros.hpp
index d373efb..2902249 100644
--- a/vulkan/vulkansc_hpp_macros.hpp
+++ b/vulkan/vulkansc_hpp_macros.hpp
@@ -28,6 +28,13 @@
 #  error "vulkansc.hpp needs at least c++ standard version 11"
 #endif
 
+// include headers holding feature-test macros
+#if 20 <= VULKAN_HPP_CPP_VERSION
+#  include <version>
+#else
+#  include <ciso646>
+#endif
+
 #if defined( VULKAN_HPP_DISABLE_ENHANCED_MODE )
 #  if !defined( VULKAN_HPP_NO_SMART_HANDLE )
 #    define VULKAN_HPP_NO_SMART_HANDLE