diff --git a/src/Core/composer.json b/src/Core/composer.json
index 2d27262dc7c1..6072c3671b46 100644
--- a/src/Core/composer.json
+++ b/src/Core/composer.json
@@ -4,14 +4,16 @@
     "license": "Apache-2.0",
     "minimum-stability": "stable",
     "require": {
-        "php": ">=5.5.9",
+        "php": ">=5.5",
         "rize/uri-template": "~0.3",
         "google/auth": "^0.11",
         "guzzlehttp/guzzle": "^5.3|^6.0",
         "guzzlehttp/psr7": "^1.2",
         "monolog/monolog": "~1",
-        "psr/http-message": "1.0.*",
-        "symfony/lock": "dev-master"
+        "psr/http-message": "1.0.*"
+    },
+    "suggest": {
+        "symfony/lock": "Required for the Spanner cached based session pool. Please require the following commit: dev-master#1ba6ac9"
     },
     "extra": {
         "component": {
diff --git a/src/Spanner/composer.json b/src/Spanner/composer.json
index 5d92a476cb9e..64d1b341b7e3 100644
--- a/src/Spanner/composer.json
+++ b/src/Spanner/composer.json
@@ -5,7 +5,7 @@
     "minimum-stability": "stable",
     "require": {
         "ext-grpc": "*",
-        "google/cloud-core": "^1.0",
+        "google/cloud-core": "^1.4",
         "google/gax": "^0.9",
         "google/proto-client-php": "^0.8"
     },