diff --git a/gatspy/periodic/lomb_scargle_fast.py b/gatspy/periodic/lomb_scargle_fast.py
index 5ae1175..46384d3 100644
--- a/gatspy/periodic/lomb_scargle_fast.py
+++ b/gatspy/periodic/lomb_scargle_fast.py
@@ -322,7 +322,11 @@ def lomb_scargle_fast(t, y, dy=1, f0=0, df=None, Nf=None,
             warnings.simplefilter("ignore")
 
         power = (YC * YC / CC + YS * YS / SS) / YY
-
+        
+        # fix power at zero frequency
+        if f0 == 0:
+            power[0] = np.mean(y ** 2 - (y - np.mean(y)) ** 2) / np.mean(y ** 2)
+        
         # fix NaN and INF at zero frequency
         if np.isnan(power[0]) or np.isinf(power[0]):
             power[0] = 0