diff --git a/app/raster_utils.py b/app/raster_utils.py
index 933adb64..91b48a25 100644
--- a/app/raster_utils.py
+++ b/app/raster_utils.py
@@ -152,11 +152,9 @@ def export_raster(input, output, **opts):
                                 ci.index(ColorInterp.alpha) + 1)
             
             # Only 2 bands (common with thermal)?
-            elif len(ci) <= 2 and ColorInterp.gray in ci and ColorInterp.alpha in ci:
-                indexes = (ci.index(ColorInterp.gray) + 1,
-                            ci.index(ColorInterp.gray) + 1,
-                            ci.index(ColorInterp.gray) + 1,
-                            ci.index(ColorInterp.alpha) + 1)
+            elif len(ci) == 2 and ColorInterp.gray in ci and ColorInterp.alpha in ci:
+                indexes = (ci.index(ColorInterp.gray) + 1,) * 3 + \
+                           (ci.index(ColorInterp.alpha) + 1, )
 
         if ColorInterp.alpha in ci:
             mask = reader.read(ci.index(ColorInterp.alpha) + 1, window=win)