diff --git a/src/pymor/discretizers/builtin/gui/gl.py b/src/pymor/discretizers/builtin/gui/gl.py
index a37619117cdae7f6f77ecba3e38dbcfd8d61bf7d..01ba76a19dc4be5b24a1575e1ff93e49b9d96272 100644
--- a/src/pymor/discretizers/builtin/gui/gl.py
+++ b/src/pymor/discretizers/builtin/gui/gl.py
@@ -129,23 +129,20 @@ if config.HAVE_QT and config.HAVE_QTOPENGL and config.HAVE_GL:
             self.shift = - np.array(bb[0]) - self.size / 2
 
             # setup buffers
+            buffer_dtype = [('position', 'f4', 2), ('color', 'f4', (1,))]
             if self.reference_element == triangle:
                 if codim == 2:
-                    self.vertex_data = np.empty(len(coordinates),
-                                                dtype=[('position', 'f4', 2), ('color', 'f4', 1)])
+                    self.vertex_data = np.empty(len(coordinates), dtype=buffer_dtype)
                     self.indices = subentities
                 else:
-                    self.vertex_data = np.empty(len(subentities) * 3,
-                                                dtype=[('position', 'f4', 2), ('color', 'f4', 1)])
+                    self.vertex_data = np.empty(len(subentities) * 3, dtype=buffer_dtype)
                     self.indices = np.arange(len(subentities) * 3, dtype=np.uint32)
             else:
                 if codim == 2:
-                    self.vertex_data = np.empty(len(coordinates),
-                                                dtype=[('position', 'f4', 2), ('color', 'f4', 1)])
+                    self.vertex_data = np.empty(len(coordinates), dtype=buffer_dtype)
                     self.indices = np.vstack((subentities[:, 0:3], subentities[:, [0, 2, 3]]))
                 else:
-                    self.vertex_data = np.empty(len(subentities) * 6,
-                                                dtype=[('position', 'f4', 2), ('color', 'f4', 1)])
+                    self.vertex_data = np.empty(len(subentities) * 6, dtype=buffer_dtype)
                     self.indices = np.arange(len(subentities) * 6, dtype=np.uint32)
             self.indices = np.ascontiguousarray(self.indices)