diff --git a/test/units/testsuite-50.sh b/test/units/testsuite-50.sh
index aa3d4d068d..6bcfb4a897 100755
--- a/test/units/testsuite-50.sh
+++ b/test/units/testsuite-50.sh
@@ -321,7 +321,7 @@ MountAPIVFS=yes
 PrivateTmp=yes
 ExecStart=/bin/sh -c ' \\
     systemd-notify --ready; \\
-    while [[ ! -f /tmp/img/usr/lib/os-release ]] || ! grep -q -F MARKER /tmp/img/usr/lib/os-release; do \\
+    while [ ! -f /tmp/img/usr/lib/os-release ] || ! grep -q -F MARKER /tmp/img/usr/lib/os-release; do \\
         sleep 0.1; \\
     done; \\
     mount; \\