diff --git a/common/functions.sh b/common/functions.sh
index fe21519..c95817a 100644
--- a/common/functions.sh
+++ b/common/functions.sh
@@ -79,7 +79,7 @@ get_system_used_space() {
 }
 
 human_readable_bytes() {
-  local spacebytes="$1"
+  local spacebytes="expr $1"
   spacekb=`expr "$spacebytes" / 1024`
   spacemb=`expr "$spacebytes" / 1024 / 1024`
   spacegb=`expr "$spacebytes" / 1024 / 1024 / 1024`