diff --git a/bitcoin.sh b/bitcoin.sh
index d2ed515..acdba18 100644
--- a/bitcoin.sh
+++ b/bitcoin.sh
@@ -17,7 +17,7 @@
 if ((BASH_VERSINFO[0] < 4))
 then
     echo "This script requires bash version 4 or above." >&2
-    return 538510
+    exit 538510
 fi
 
 declare -a base58=(