diff --git a/gdal/swig/python/scripts/gdal2tiles.py b/gdal/swig/python/scripts/gdal2tiles.py
index dd169c3b5e8f..106d4c8e8352 100755
--- a/gdal/swig/python/scripts/gdal2tiles.py
+++ b/gdal/swig/python/scripts/gdal2tiles.py
@@ -2867,8 +2867,8 @@ def single_threaded_tiling(input_file, output_folder, options):
 def multi_threaded_tiling(input_file, output_folder, options):
     nb_processes = options.nb_processes or 1
 
-    # Make sure that all processes do not consume more than GDAL_CACHEMAX
-    os.environ['GDAL_CACHEMAX'] = '%d' % int(gdal.GetCacheMax() / nb_processes)
+    # Make sure that all processes do not consume more than `gdal.GetCacheMax()`
+    os.environ['GDAL_CACHEMAX'] = '%d' % max(1, int(gdal.GetCacheMax() / 1024 / 1024 / nb_processes))
 
     (conf_receiver, conf_sender) = Pipe(False)