diff --git a/masque/test/test_file_roundtrip.py b/masque/test/test_file_roundtrip.py
index c7536a5..6933d61 100644
--- a/masque/test/test_file_roundtrip.py
+++ b/masque/test/test_file_roundtrip.py
@@ -5,11 +5,13 @@ from numpy.testing import assert_allclose
 
 from ..pattern import Pattern
 from ..library import Library
-from ..file import gdsii, oasis
 from ..shapes import Path as MPath, Circle, Polygon
 from ..repetition import Grid, Arbitrary
 
 def create_test_library(for_gds: bool = False) -> Library:
+    from ..file import gdsii
+    if not for_gds:
+        from ..file import oasis
     lib = Library()
 
     # 1. Polygons
@@ -62,6 +64,7 @@ def create_test_library(for_gds: bool = False) -> Library:
     return lib
 
 def test_gdsii_full_roundtrip(tmp_path: Path) -> None:
+    from ..file import gdsii
     lib = create_test_library(for_gds=True)
     gds_file = tmp_path / "full_test.gds"
     gdsii.writefile(lib, gds_file, meters_per_unit=1e-9)
@@ -110,6 +113,7 @@ def test_gdsii_full_roundtrip(tmp_path: Path) -> None:
 
 def test_oasis_full_roundtrip(tmp_path: Path) -> None:
     pytest.importorskip("fatamorgana")
+    from ..file import oasis
     lib = create_test_library(for_gds=False)
     oas_file = tmp_path / "full_test.oas"
     oasis.writefile(lib, oas_file, units_per_micron=1000)
diff --git a/masque/test/test_oasis.py b/masque/test/test_oasis.py
index faffa58..b1129f4 100644
--- a/masque/test/test_oasis.py
+++ b/masque/test/test_oasis.py
@@ -4,12 +4,10 @@ from numpy.testing import assert_equal
 
 from ..pattern import Pattern
 from ..library import Library
-from ..file import oasis
-
-
 def test_oasis_roundtrip(tmp_path: Path) -> None:
     # Skip if fatamorgana is not installed
     pytest.importorskip("fatamorgana")
+    from ..file import oasis
 
     lib = Library()
     pat1 = Pattern()