diff --git a/src/ocamldep.ml b/src/ocamldep.ml
index fc4a12e1..b43117e4 100644
--- a/src/ocamldep.ml
+++ b/src/ocamldep.ml
@@ -139,9 +139,13 @@ let rules ~(ml_kind:Ml_kind.t) ~dir ~modules
               );
             let build_paths dependencies =
               let dependency_file_path m =
-                Option.map
-                  (Module.file ~dir m Ml_kind.Intf)
-                 ~f:all_deps_path
+                let path =
+                  match Module.file ~dir m Ml_kind.Intf with
+                  | Some _ as x -> x
+                  | None when Option.is_some alias_module -> None
+                  | None -> Module.file ~dir m Ml_kind.Impl
+                in
+                Option.map path ~f:all_deps_path
               in
               List.filter_map dependencies ~f:dependency_file_path
             in
diff --git a/test/blackbox-tests/test-cases/github660/run.t b/test/blackbox-tests/test-cases/github660/run.t
index ed5c2704..2b37f52e 100644
--- a/test/blackbox-tests/test-cases/github660/run.t
+++ b/test/blackbox-tests/test-cases/github660/run.t
@@ -16,6 +16,5 @@ to rely on these.
   hello
   $ echo 'let x = 1' >> no-interfaces/lib_sub.ml
   $ jbuilder runtest --root no-interfaces --display quiet -j1 2>&1 | grep -v Entering | grep -v ocamlopt
-  File "_none_", line 1:
-  Error: Files .main.eobjs/main.cmx and .main.eobjs/lib_sub.cmx
-         make inconsistent assumptions over interface Lib_sub
+          main alias runtest
+  hello