diff --git a/gnu/packages/ocaml.scm b/gnu/packages/ocaml.scm
index 81e967cd34..6fe8cb46f9 100644
--- a/gnu/packages/ocaml.scm
+++ b/gnu/packages/ocaml.scm
@@ -1498,9 +1498,8 @@ (define-public ocaml-frontc
 archive(native) = \"frontc.cmxa\""))))
                (symlink (string-append out "/lib/ocaml/frontc")
                         (string-append out "/lib/ocaml/FrontC"))))))
-       #:make-flags (list (string-append "PREFIX="
-                                         (assoc-ref %outputs "out"))
-                          "OCAML_SITE=$(LIB_DIR)/ocaml/")))
+       #:make-flags ,#~(list (string-append "PREFIX=" #$output)
+                             "OCAML_SITE=$(LIB_DIR)/ocaml/")))
     (properties `((upstream-name . "FrontC")))
     (home-page "https://www.irit.fr/FrontC")
     (synopsis "C parser and lexer library")