diff --git a/src/php/tests/qps/composer.json b/src/php/tests/qps/composer.json
index f8512648c4a..0f4b0c04ba4 100644
--- a/src/php/tests/qps/composer.json
+++ b/src/php/tests/qps/composer.json
@@ -1,7 +1,7 @@
 {
   "require": {
     "grpc/grpc": "dev-master",
-    "google/protobuf": "v3.4.1"
+    "google/protobuf": "v3.5.1.1"
   },
   "autoload": {
     "psr-4": {