bin/cleanup: remove bashism

1 files changed, 1 insertions, 1 deletions

diff --git a/bin/cleanup b/bin/cleanup
index 4d827ee..aa93004 100755
--- a/bin/cleanup
+++ b/bin/cleanup
@@ -44,7 +44,7 @@ ls "${build_log_directory}" | \
       if [ ${count} -ge 10 ]; then
         echo "${build_log_directory}/${a}"
       fi
-      count=$[${count}+1]
+      count=$((${count}+1))
     done
   ) | \
   xargs -rn1 rm