diff --git a/src/context/typecore.ml b/src/context/typecore.ml
index dc38a5264..0c3ebde9f 100644
--- a/src/context/typecore.ml
+++ b/src/context/typecore.ml
@@ -294,7 +294,7 @@ let add_local ctx k n t p =
 			begin try
 				let v' = PMap.find n ctx.locals in
 				(* ignore std lib *)
-				if not (List.exists (ExtLib.String.starts_with p.pfile) ctx.com.std_path) then begin
+				if not (List.exists (ExtLib.String.starts_with ~prefix:p.pfile) ctx.com.std_path) then begin
 					warning ctx WVarShadow "This variable shadows a previously declared variable" p;
 					warning ~depth:1 ctx WVarShadow (compl_msg "Previous variable was here") v'.v_pos
 				end
diff --git a/src/optimization/dce.ml b/src/optimization/dce.ml
index 4e7b1fc98..90d8fc5d6 100644
--- a/src/optimization/dce.ml
+++ b/src/optimization/dce.ml
@@ -76,7 +76,7 @@ let overrides_extern_field cf c =
 	loop c cf
 
 let is_std_file dce file =
-	List.exists (ExtString.String.starts_with file) dce.std_dirs
+	List.exists (ExtString.String.starts_with ~prefix:file) dce.std_dirs
 
 let keep_metas = [Meta.Keep;Meta.Expose]