diff --git a/opendm/dem/commands.py b/opendm/dem/commands.py
index 0b0bcce0..37ed4456 100755
--- a/opendm/dem/commands.py
+++ b/opendm/dem/commands.py
@@ -186,7 +186,7 @@ def create_dem(input_point_cloud, dem_type, output_type='max', radiuses=['0.56']
     for t in tiles: 
         if not os.path.exists(t['filename']):
             raise Exception("Error creating %s, %s failed to be created" % (output_file, t['filename']))
-    
+
     # Create virtual raster
     tiles_vrt_path = os.path.abspath(os.path.join(outdir, "tiles.vrt"))
     tiles_file_list = os.path.abspath(os.path.join(outdir, "tiles_list.txt"))
@@ -315,6 +315,8 @@ def median_smoothing(geotiff_path, output_path, smoothing_iterations=1):
         dtype = img.dtypes[0]
         arr = img.read()[0]
 
+        nodata_locs = numpy.where(arr == nodata)
+
         # Median filter (careful, changing the value 5 might require tweaking)
         # the lines below. There's another numpy function that takes care of 
         # these edge cases, but it's slower.
@@ -330,8 +332,7 @@ def median_smoothing(geotiff_path, output_path, smoothing_iterations=1):
             arr[-1][-2:] = arr[-2][-1] = arr[-2][-2]
 
         # Median filter leaves a bunch of zeros in nodata areas
-        locs = numpy.where(arr == 0.0)
-        arr[locs] = nodata
+        arr[nodata_locs] = nodata
 
         # write output
         with rasterio.open(output_path, 'w', **img.profile) as imgout: