diff --git a/.travis.yml b/.travis.yml
index 3690bab81..2aa8c9fce 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,6 +13,11 @@ before_install:
 install:
   - python3 setup.py install
 script:
-  - python3 -c 'import klayout.db as db; dir(db)'
-  - python3 -c 'import klayout.rdb as rdb; dir(rdb)'
-  - python3 -c 'import klayout.tl as tl; dir(tl)'
+  - python3 -c 'import klayout.db as db; print(dir(db))'
+  - python3 -c 'import klayout.rdb as rdb; print(dir(rdb))'
+  - python3 -c 'import klayout.tl as tl; print(dir(tl))'
+  - python3 -c 'import klayout._db as db; print(dir(db))'
+  - python3 -c 'import klayout._rdb as rdb; print(dir(rdb))'
+  - python3 -c 'import klayout._tl as tl; print(dir(tl))'
+  - python3 -c 'import klayout._gsi as gsi; print(dir(gsi))'
+  - python3 -c 'import klayout._pya as pya; print(dir(pya))'