diff --git a/compiler/lib/linker.ml b/compiler/lib/linker.ml
index d9c93b3002..a49cd797d2 100644
--- a/compiler/lib/linker.ml
+++ b/compiler/lib/linker.ml
@@ -186,7 +186,14 @@ module Fragment = struct
     List.fold_left
       ~f:(fun m (k, v) -> StringMap.add k v m)
       ~init:StringMap.empty
-      [ "js-string", Config.Flag.use_js_string; "effects", Config.Flag.effects ]
+      [ "js-string", Config.Flag.use_js_string
+      ; "effects", Config.Flag.effects
+      ; ( "wasm"
+        , fun () ->
+            match Config.target () with
+            | `JavaScript -> false
+            | `Wasm -> true )
+      ]
 
   type t =
     | Always_include of Javascript.program pack
diff --git a/runtime/sys.js b/runtime/sys.js
index 92c402bbd7..14f4c76241 100644
--- a/runtime/sys.js
+++ b/runtime/sys.js
@@ -357,6 +357,7 @@ function caml_sys_is_regular_file(name) {
 }
 //Always
 //Requires: caml_fatal_uncaught_exception
+//If: !wasm
 function caml_setup_uncaught_exception_handler() {
   var process = globalThis.process;
   if(process && process.on) {