diff --git a/macos-guest-virtualbox.sh b/macos-guest-virtualbox.sh
index b6d9775..d03ad64 100755
--- a/macos-guest-virtualbox.sh
+++ b/macos-guest-virtualbox.sh
@@ -2,7 +2,7 @@
 # Semi-automatic installer of macOS on VirtualBox
 # (c) myspaghetti, licensed under GPL2.0 or higher
 # url: https://github.com/myspaghetti/macos-guest-virtualbox
-# version 0.77.7
+# version 0.77.8
 
 # Requirements: 40GB available storage on host
 # Dependencies: bash >= 4.0, unzip, wget, dmg2img,
@@ -147,6 +147,9 @@ if [ -n "$(gcsplit --help 2>/dev/null)" ]; then
     function base64() {
         gbase64 "$@"
     }
+    function expr() {
+        gexpr "$@"
+    }
 fi
 }