diff --git a/Userland/Libraries/LibJS/Runtime/FunctionKind.h b/Userland/Libraries/LibJS/Runtime/FunctionKind.h
index 41b53001e9..62edbb317b 100644
--- a/Userland/Libraries/LibJS/Runtime/FunctionKind.h
+++ b/Userland/Libraries/LibJS/Runtime/FunctionKind.h
@@ -8,7 +8,7 @@
 
 namespace JS {
 
-enum class FunctionKind {
+enum class FunctionKind : u8 {
     Normal,
     Generator,
     Async,