diff --git a/include/vulkan/vulkan_from_string.hpp b/include/vulkan/vulkan_from_string.hpp
index f70dd34..6e3c76d 100644
--- a/include/vulkan/vulkan_from_string.hpp
+++ b/include/vulkan/vulkan_from_string.hpp
@@ -4401,7 +4401,10 @@ namespace VULKAN_HPP_NAMESPACE
   VULKAN_HPP_STORAGE_API extern const EnumFromStringMap enumFromStringMap;
 
   template <typename TEnum>
-  std::optional<TEnum> from_string( const std::string & );
+  std::optional<TEnum> from_string( const std::string & )
+  {
+      static_assert(false, "Not a Vulkan enum type.");
+  }
 
   //=== VK_VERSION_1_0 ===