diff --git a/spanner/cloud-client/requirements.txt b/spanner/cloud-client/requirements.txt
index 4d374891d4d..06551559ee2 100644
--- a/spanner/cloud-client/requirements.txt
+++ b/spanner/cloud-client/requirements.txt
@@ -1,2 +1,2 @@
 google-cloud-spanner==1.2.0
-futures ; python_version < '3'
+futures==3.2.0; python_version < "3"