diff --git a/README.md b/README.md
index c4459f6..4b91d4e 100644
--- a/README.md
+++ b/README.md
@@ -141,9 +141,9 @@ enum class Color { RED = 2, BLUE = 4, GREEN = 8 };
 * Enum fusion for multi-level switch/case statements
 
   ```cpp
-  switch (magic_enum::enum_fuse(color, direction)) {
-    case magic_enum::enum_fuse(Color::RED, Directions::Up): // ...
-    case magic_enum::enum_fuse(Color::BLUE, Directions::Down): // ...
+  switch (magic_enum::enum_fuse(color, direction).value()) {
+    case magic_enum::enum_fuse(Color::RED, Directions::Up).value(): // ...
+    case magic_enum::enum_fuse(Color::BLUE, Directions::Down).value(): // ...
   // ...
   }
   ```
diff --git a/doc/reference.md b/doc/reference.md
index a42580f..9266752 100644
--- a/doc/reference.md
+++ b/doc/reference.md
@@ -330,7 +330,7 @@ constexpr string_view enum_type_name() noexcept;
 
 ```cpp
 template <typename... Es>
-[[nodiscard]] constexpr std::size_t enum_fuse(Es... values);
+[[nodiscard]] constexpr optional<std::uintmax_t> enum_fuse(Es... values);
 ```
 
 * Returns a bijective mix of several enum values. This can be used to emulate 2D switch/case statements.
@@ -338,9 +338,9 @@ template <typename... Es>
 * Examples
 
   ```cpp
-  switch (magic_enum::enum_fuse(color, direction)) {
-    case magic_enum::enum_fuse(Color::RED, Directions::Up): // ...
-    case magic_enum::enum_fuse(Color::BLUE, Directions::Down): // ...
+  switch (magic_enum::enum_fuse(color, direction).value()) {
+    case magic_enum::enum_fuse(Color::RED, Directions::Up).value(): // ...
+    case magic_enum::enum_fuse(Color::BLUE, Directions::Down).value(): // ...
   // ...
   }
   ```