diff --git a/src/data/DamarisFFT.py b/src/data/DamarisFFT.py
index e29998f..11a56c5 100644
--- a/src/data/DamarisFFT.py
+++ b/src/data/DamarisFFT.py
@@ -230,9 +230,9 @@ class DamarisFFT:
         """
         Return result scaled to PPM compared to f_ref
 
-        :param f_ref: larmor frequency in Hz
+        :param f_ref: larmor frequency in MHz
         :return:
         """
-        self.x /= f_ref*1e6
+        self.x /= f_ref
         self.set_xlabel( "PPM" )
         return self
\ No newline at end of file