diff --git a/.gitignore b/.gitignore
index 8d35cb3..2314fef 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 __pycache__
 *.pyc
+.cache
+*.vt*
diff --git a/test.py b/test.py
deleted file mode 100644
index 22b0bb8..0000000
--- a/test.py
+++ /dev/null
@@ -1,28 +0,0 @@
-from writer import *
-from data_array import *
-from vtk_files import *
-import numpy as np
-
-N = 10
-
-x = np.linspace(0, 1, N*2)
-y = np.linspace(0, 1, N+2)
-z = np.linspace(0, 1, N)
-
-rect = RectilinearGrid('test.vtr', (x, y, z))
-
-x, y, z = np.meshgrid(x, y, z, indexing='ij')
-r = np.sqrt(x**2 + y**2 + z**2)
-e_r = np.zeros(r.shape + (3,3))
-e_r[0, 0, 0, :, :] = np.array([[0, 1, 0], [1, 0, 0], [0, 1, 1]])
-e_r[-1, 0, 0, :, :] = np.eye(3)
-print(e_r.shape)
-rect.addPointData(DataArray(r, range(3), 'R'))
-rect.addPointData(DataArray(r, range(3), 'R2'))
-rect.addPointData(DataArray(e_r, range(3), 'e_r'))
-rect.write()
-
-from evtk.hl import gridToVTK
-
-e_r = e_r.transpose(4, 3, 0, 1, 2).copy()
-gridToVTK('grid', x, y, z, pointData={'R': r, 'R2':r, 'e_r': e_r})
diff --git a/tests/test_rectilinear_grid.py b/tests/test_rectilinear_grid.py
new file mode 100644
index 0000000..5e4d74f
--- /dev/null
+++ b/tests/test_rectilinear_grid.py
@@ -0,0 +1,22 @@
+from uvw import RectilinearGrid, DataArray
+import numpy as np
+
+def test_rectilinear_grid():
+    N = 10
+
+    x = np.linspace(0, 1, N*2)
+    y = np.linspace(0, 1, N+2)
+    z = np.linspace(0, 1, N)
+
+    rect = RectilinearGrid('test.vtr', (x, y, z))
+
+    x, y, z = np.meshgrid(x, y, z, indexing='ij')
+    r = np.sqrt(x**2 + y**2 + z**2)
+    e_r = np.zeros(r.shape + (3,3))
+    e_r[0, 0, 0, :, :] = np.array([[0, 1, 0], [1, 0, 0], [0, 1, 1]])
+    e_r[-1, 0, 0, :, :] = np.eye(3)
+    print(e_r.shape)
+    rect.addPointData(DataArray(r, range(3), 'R'))
+    rect.addPointData(DataArray(r, range(3), 'R2'))
+    rect.addPointData(DataArray(e_r, range(3), 'e_r'))
+    rect.write()
diff --git a/uvw/__init__.py b/uvw/__init__.py
new file mode 100644
index 0000000..d9ecccd
--- /dev/null
+++ b/uvw/__init__.py
@@ -0,0 +1,2 @@
+from .vtk_files import *
+from .data_array import *
diff --git a/data_array.py b/uvw/data_array.py
similarity index 100%
rename from data_array.py
rename to uvw/data_array.py
diff --git a/vtk_files.py b/uvw/vtk_files.py
similarity index 91%
rename from vtk_files.py
rename to uvw/vtk_files.py
index 17960cd..d155a24 100644
--- a/vtk_files.py
+++ b/uvw/vtk_files.py
@@ -1,65 +1,65 @@
-from writer import *
-from data_array import *
+from . import writer
+from . import data_array
 
 import functools
 
 class VTKFile:
     """Generic VTK file"""
     def __init__(self, filename, filetype, rank=None):
         self.filename = filename
         self.rank = rank
-        self.writer = Writer(filetype)
+        self.writer = writer.Writer(filetype)
 
     def addPointData(self, data_array):
         self.point_data.registerDataArray(data_array)
 
     def addCellData(self, data_array):
         self.cell_data.registerDataArray(data_array)
 
     def write(self):
         self.writer.registerAppend()
         self.writer.write(self.filename)
 
 
 class RectilinearGrid(VTKFile):
     """VTK Rectilinear grid (coordinates are given by 3 seperate ranges)"""
     def __init__(self, filename, coordinates, rank=None):
         VTKFile.__init__(self, filename, 'RectilinearGrid', rank)
 
         # Checking that we actually have a list or tuple
         if type(coordinates).__name__ not in ('tuple', 'list'):
             coordinates = [coordinates]
 
         self.coordinates = list(coordinates)
 
         # Filling in missing coordinates
         for _ in range(len(coordinates), 3):
             self.coordinates.append(np.array([0.]))
 
         # Setting data extent
         extent = []
 
         for coord in self.coordinates:
             if coord.ndim != 1:
                 raise Exception('Coordinate array should have only one dimension')
             extent.append(coord.size-1)
 
         extent = functools.reduce(lambda x, y: x + "0 {} ".format(y), extent, "")
         self.writer.setDataNodeAttributes({
             "WholeExtent": extent
         })
 
         self.piece = self.writer.registerPiece({
             "Extent": extent
         })
 
         # Registering coordinates
         coordinate_component = self.piece.register('Coordinates')
 
         for coord, prefix in zip(self.coordinates, ('x', 'y', 'z')):
-            array = DataArray(coord, [0], prefix + '_coordinates')
+            array = data_array.DataArray(coord, [0], prefix + '_coordinates')
             coordinate_component.registerDataArray(array)
 
         # Registering data elements
         self.point_data = self.piece.register('PointData')
         self.cell_data = self.piece.register('CellData')
diff --git a/writer.py b/uvw/writer.py
similarity index 100%
rename from writer.py
rename to uvw/writer.py