diff --git a/t/t7406-submodule-update.sh b/t/t7406-submodule-update.sh
index dda3929..68ea31d 100755
--- a/t/t7406-submodule-update.sh
+++ b/t/t7406-submodule-update.sh
@@ -14,8 +14,8 @@
 
 compare_head()
 {
-    sha_master=`git rev-list --max-count=1 master`
-    sha_head=`git rev-list --max-count=1 HEAD`
+    sha_master=$(git rev-list --max-count=1 master)
+    sha_head=$(git rev-list --max-count=1 HEAD)
 
     test "$sha_master" = "$sha_head"
 }