diff --git a/xgm.py b/xgm.py
index ddb9eec7fb7d0759f7603acaa1b28b31d5a655aa..5446cbf9a9d7ba147a802b697161dc4d000eca10 100644
--- a/xgm.py
+++ b/xgm.py
@@ -600,13 +600,13 @@ def timFactorFromTable(voltage, photonEnergy, mcp=1):
             f: calibration factor in microjoule per APD signal
     '''
     energies = np.sort([key for key in tim_calibration_table])
-    if photonEnergy not in photon_energies:
+    if photonEnergy not in energies:
         if photonEnergy > energies.max():
             photonEnergy = energies.max()
         elif photonEnergy < energies.min():
             photonEnergy = energies.min()
         else:
-            idx = np.searchsorted(photon_energies, energy) - 1
+            idx = np.searchsorted(energies, photonEnergy) - 1
             polyA = np.poly1d(tim_calibration_table[energies[idx]][mcp-1])
             polyB = np.poly1d(tim_calibration_table[energies[idx+1]][mcp-1])
             fA = -np.exp(polyA(voltage))