diff --git a/src/dune/preprocessing.ml b/src/dune/preprocessing.ml
index d9addc8fa15..ea5d9fff1b3 100644
--- a/src/dune/preprocessing.ml
+++ b/src/dune/preprocessing.ml
@@ -581,7 +581,7 @@ let make sctx ~dir ~expander ~dep_kind ~lint ~preprocess ~preprocessor_deps
   in
   let preprocessor_deps =
     let loc, deps = preprocessor_deps in
-    ( if (not (is_preprocessing preprocess)) && not (List.is_empty deps) then
+    ( if not (is_preprocessing preprocess) && not (List.is_empty deps) then
       let is_error = Dune_project.dune_version (Scope.project scope) >= (2, 0) in
       User_warning.emit ~loc ~is_error
         [ Pp.text