diff --git a/ocr_pyflow b/ocr_pyflow
index ad6beb0..1ac635e 100755
--- a/ocr_pyflow
+++ b/ocr_pyflow
@@ -49,7 +49,7 @@ def parse_arguments():
                         help="Keep intermediate files.",
                         required=False)
     parser.add_argument("--nCores",
-                        default=multiprocessing.cpu_count(),
+                        default=min(4, multiprocessing.cpu_count()),
                         dest="nCores",
                         help="Total number of cores available.",
                         required=False,