diff --git a/src/seismic_hazard_forecasting.py b/src/seismic_hazard_forecasting.py
index 4606470..fda2af5 100644
--- a/src/seismic_hazard_forecasting.py
+++ b/src/seismic_hazard_forecasting.py
@@ -858,7 +858,7 @@ verbose: {verbose}")
 
             iml_grid_hd = iml_grid_prep[j]   
             #vmin_hd = min(x for x in iml_grid_hd.flatten() if not isnan(x))
-            vmax_hd = np.nanmax(iml_grid_hd.flatten())
+            vmax_hd = np.nanmax(iml_grid_hd)
 
             # generate image overlay
             north, south = lat.max(), lat.min()  # Latitude range