diff --git a/composer.json b/composer.json
index 6ae3318..2f27c83 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
     "require": {
         "ext-grpc": "*",
         "grpc/grpc": "1.22",
-        "google/protobuf": "3.8.0"
+        "google/protobuf": "3.15.0"
     },
     "config": {
         "bin-dir": "bin"
diff --git a/composer.lock b/composer.lock
index b5d6dbb..10dceda 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,20 +4,20 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "df4f984436c2492acc305611aec8a578",
+    "content-hash": "4d5dbe65b975c5de8430a4c8acbeea63",
     "packages": [
         {
             "name": "google/protobuf",
-            "version": "v3.8.0",
+            "version": "v3.15.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/protocolbuffers/protobuf-php.git",
-                "reference": "a257235dc1a0d45f8cfc641d0c2ad852f57396c4"
+                "reference": "758a0ef01c7bdf20d7ff31295d2af872547cc072"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/protocolbuffers/protobuf-php/zipball/a257235dc1a0d45f8cfc641d0c2ad852f57396c4",
-                "reference": "a257235dc1a0d45f8cfc641d0c2ad852f57396c4",
+                "url": "https://api.github.com/repos/protocolbuffers/protobuf-php/zipball/758a0ef01c7bdf20d7ff31295d2af872547cc072",
+                "reference": "758a0ef01c7bdf20d7ff31295d2af872547cc072",
                 "shasum": ""
             },
             "require": {
@@ -45,7 +45,11 @@
             "keywords": [
                 "proto"
             ],
-            "time": "2019-05-29T00:06:29+00:00"
+            "support": {
+                "issues": "https://github.com/protocolbuffers/protobuf-php/issues",
+                "source": "https://github.com/protocolbuffers/protobuf-php/tree/v3.15.0"
+            },
+            "time": "2021-02-18T22:06:03+00:00"
         },
         {
             "name": "grpc/grpc",
@@ -98,5 +102,6 @@
     "platform": {
         "ext-grpc": "*"
     },
-    "platform-dev": []
+    "platform-dev": [],
+    "plugin-api-version": "2.2.0"
 }