diff --git a/pygsp/graphs/nngraphs/sphereicosahedron.py b/pygsp/graphs/nngraphs/sphereicosahedron.py
index a2553f15..4d00edda 100644
--- a/pygsp/graphs/nngraphs/sphereicosahedron.py
+++ b/pygsp/graphs/nngraphs/sphereicosahedron.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 
+import log
 import numpy as np
 
 from pygsp.graphs import NNGraph  # prevent circular import in Python < 3.5
@@ -315,7 +316,7 @@ def _float_to_int(self, data, digits=None, dtype=np.int32):
         if digits is None:
             digits = self._decimal_to_digits(1e-8)
         elif isinstance(digits, float) or isinstance(digits, np.float):
-            digits = _decimal_to_digits(digits)
+            digits = self._decimal_to_digits(digits)
         elif not (isinstance(digits, int) or isinstance(digits, np.integer)):
             log.warn('Digits were passed as %s!', digits.__class__.__name__)
             raise ValueError('Digits must be None, int, or float!')