diff --git a/t/lib-parallel-checkout.sh b/t/lib-parallel-checkout.sh
index 21f5759..83b279a 100644
--- a/t/lib-parallel-checkout.sh
+++ b/t/lib-parallel-checkout.sh
@@ -27,7 +27,7 @@
 	rm -f "$trace_file" &&
 	GIT_TRACE2="$(pwd)/$trace_file" "$@" 2>&8 &&
 
-	local workers=$(grep "child_start\[..*\] git checkout--worker" "$trace_file" | wc -l) &&
+	local workers="$(grep "child_start\[..*\] git checkout--worker" "$trace_file" | wc -l)" &&
 	test $workers -eq $expected_workers &&
 	rm "$trace_file"
 } 8>&2 2>&4