diff --git a/pyeeg/entropy.py b/pyeeg/entropy.py
index ebd4467..bfe7c88 100644
--- a/pyeeg/entropy.py
+++ b/pyeeg/entropy.py
@@ -1,6 +1,6 @@
 import numpy
 from .embedded_sequence import embed_seq
-
+from .spectrum import bin_power
 
 def ap_entropy(X, M, R):
     """Computer approximate entropy (ApEN) of series X, specified by M and R.