diff --git a/tests/unused_func/Simple.t/custom_demo.ml b/tests/unused_func/Simple.t/custom_demo.ml
new file mode 100644
index 0000000..3c0aa15
--- /dev/null
+++ b/tests/unused_func/Simple.t/custom_demo.ml
@@ -0,0 +1 @@
+let ()  = print_int (Custom_lib.Custom_lib_impl.incr 41)
\ No newline at end of file
diff --git a/tests/unused_func/Simple.t/custom_lib_impl.ml b/tests/unused_func/Simple.t/custom_lib_impl.ml
new file mode 100644
index 0000000..7bf41f3
--- /dev/null
+++ b/tests/unused_func/Simple.t/custom_lib_impl.ml
@@ -0,0 +1 @@
+let incr n = n+1
\ No newline at end of file
diff --git a/tests/unused_func/Simple.t/custom_lib_impl.mli b/tests/unused_func/Simple.t/custom_lib_impl.mli
new file mode 100644
index 0000000..710be65
--- /dev/null
+++ b/tests/unused_func/Simple.t/custom_lib_impl.mli
@@ -0,0 +1 @@
+val incr : int -> int
diff --git a/tests/unused_func/Simple.t/dune b/tests/unused_func/Simple.t/dune
index 209b92f..f75f064 100644
--- a/tests/unused_func/Simple.t/dune
+++ b/tests/unused_func/Simple.t/dune
@@ -6,10 +6,17 @@
   SecondTU
   ;
   )
- ;  (flags
- ;   (:standard -dtypedtree))
  (inline_tests)
  (preprocess
-  (pps ppx_expect ppx_inline_test))
- ;(libraries base angstrom)
- )
+  (pps ppx_expect ppx_inline_test)))
+
+(library
+ (name custom_lib)
+ (public_name Simple.Custom)
+ ;(package Simple)
+ (modules custom_lib_impl))
+
+(executable
+ (name custom_demo)
+ (modules custom_demo)
+ (libraries custom_lib))
diff --git a/tests/unused_func/Simple.t/dune-project b/tests/unused_func/Simple.t/dune-project
index 0171005..9a4c4bf 100644
--- a/tests/unused_func/Simple.t/dune-project
+++ b/tests/unused_func/Simple.t/dune-project
@@ -1,3 +1,6 @@
 (lang dune 2.8)
 
 (cram enable)
+
+(package
+ (name Simple))
diff --git a/tests/unused_func/Simple.t/run.t b/tests/unused_func/Simple.t/run.t
index d3ab843..7c66e65 100644
--- a/tests/unused_func/Simple.t/run.t
+++ b/tests/unused_func/Simple.t/run.t
@@ -1,5 +1,8 @@
-  $ dune build
+  $ dune build @check
 $ dune describe
   $ zanuda -unused-decls .
+  module "Custom_lib" is omitted
   unused decl: Simple.Meow.meow
   unused decl: Simple.Meow.woof
+  unused decl: Custom_lib_impl.incr
+# Custom_lib_impl.incr is not found because a custom public name for library 'custom_lib'