diff --git a/lib/waipy/cwa/cross_wavelet.py b/lib/waipy/cwa/cross_wavelet.py
index f95e638..726285b 100644
--- a/lib/waipy/cwa/cross_wavelet.py
+++ b/lib/waipy/cwa/cross_wavelet.py
@@ -16,7 +16,7 @@
 import pylab
 from pylab import *
 import matplotlib.pyplot as plt
-import cmath
+import math # for compatibility in the new python versions
 import pandas as pd