diff --git a/test/blackbox-tests/test-cases/merlin-tests/lib/jbuild b/test/blackbox-tests/test-cases/merlin-tests/lib/jbuild
index 5a288279..02d88c23 100644
--- a/test/blackbox-tests/test-cases/merlin-tests/lib/jbuild
+++ b/test/blackbox-tests/test-cases/merlin-tests/lib/jbuild
@@ -1,4 +1,10 @@
 (library
  ((name foo)
   (libraries (bytes unix findlib))
+  (modules ())
+  (preprocess (pps (fooppx)))))
+
+(library
+ ((name bar)
+  (modules ())
   (preprocess (pps (fooppx)))))
diff --git a/test/blackbox-tests/test-cases/merlin-tests/run.t b/test/blackbox-tests/test-cases/merlin-tests/run.t
index 2531cc6f..965c9b6a 100644
--- a/test/blackbox-tests/test-cases/merlin-tests/run.t
+++ b/test/blackbox-tests/test-cases/merlin-tests/run.t
@@ -17,13 +17,18 @@
   S $LIB_PREFIX/lib/findlib
   S $LIB_PREFIX/lib/ocaml
   # Processing lib/.merlin
+  B ../_build/default/lib/.bar.objs
   B ../_build/default/lib/.foo.objs
   B $LIB_PREFIX/lib/bytes
   B $LIB_PREFIX/lib/findlib
   B $LIB_PREFIX/lib/ocaml
-  FLG -open Foo -w -40
-  FLG -ppx '$PPX/fooppx@/ppx.exe --as-ppx --cookie '\''library-name="foo"'\'''
+  FLG -open Foo -w -40 -open Bar -w -40
   S .
   S $LIB_PREFIX/lib/bytes
   S $LIB_PREFIX/lib/findlib
   S $LIB_PREFIX/lib/ocaml
+
+Make sure a ppx directive is generated
+
+  $ grep -q ppx lib/.merlin
+  [1]