diff --git a/kwant/graph/slicer.pyx b/kwant/graph/slicer.pyx
index 68c78f4b4a9300b1c84da41043729976ff0357d4..0ddcd48f014d76a9d084ebba6a215d1b61dcbe9b 100644
--- a/kwant/graph/slicer.pyx
+++ b/kwant/graph/slicer.pyx
@@ -13,7 +13,10 @@ from libc.string cimport memcpy
 from .defs cimport gint
 from .defs import gint_dtype
 from .core cimport CGraph
-from . cimport c_slicer
+
+cimport c_slicer
+# TODO: Once cythonize() no longer warns about it, replace the above be
+# from . cimport c_slicer
 
 __all__ = ['slice']