diff --git a/.github/workflows/continuous-deployment.yml b/.github/workflows/continuous-deployment.yml
index 31f85cbc..d24ec074 100644
--- a/.github/workflows/continuous-deployment.yml
+++ b/.github/workflows/continuous-deployment.yml
@@ -8,7 +8,7 @@ on:
       - "**"
 
 env:
-  COMPOSER_VERSION: "1.9.3"
+  COMPOSER_VERSION: "1.10.0"
   REQUIRED_PHP_EXTENSIONS: "mbstring"
 
 jobs:
diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index b0b86635..5388dbdb 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -9,7 +9,7 @@ on:
       - "master"
 
 env:
-  COMPOSER_VERSION: "1.9.3"
+  COMPOSER_VERSION: "1.10.0"
   REQUIRED_PHP_EXTENSIONS: "mbstring"
 
 jobs:
diff --git a/composer.json b/composer.json
index e12218c0..9f0ad344 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,7 @@
     "localheinz/diff": "^1.0.1"
   },
   "require-dev": {
-    "composer/composer": "^1.7.0",
+    "composer/composer": "^1.10.0",
     "ergebnis/license": "~0.1.0",
     "ergebnis/php-cs-fixer-config": "^2.1.0",
     "ergebnis/phpstan-rules": "~0.14.3",
diff --git a/composer.lock b/composer.lock
index 4a9760f9..3c5d4a14 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "03be0e997c801f1da7f6a88ebfd9a772",
+    "content-hash": "8120138a70d779d72e330c8215579a51",
     "packages": [
         {
             "name": "ergebnis/json-normalizer",
@@ -435,16 +435,16 @@
         },
         {
             "name": "composer/composer",
-            "version": "1.9.1",
+            "version": "1.10.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/composer/composer.git",
-                "reference": "bb01f2180df87ce7992b8331a68904f80439dd2f"
+                "reference": "472c917b2a083ec7d2fa25c55fd099d1300e2515"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/composer/composer/zipball/bb01f2180df87ce7992b8331a68904f80439dd2f",
-                "reference": "bb01f2180df87ce7992b8331a68904f80439dd2f",
+                "url": "https://api.github.com/repos/composer/composer/zipball/472c917b2a083ec7d2fa25c55fd099d1300e2515",
+                "reference": "472c917b2a083ec7d2fa25c55fd099d1300e2515",
                 "shasum": ""
             },
             "require": {
@@ -457,17 +457,17 @@
                 "psr/log": "^1.0",
                 "seld/jsonlint": "^1.4",
                 "seld/phar-utils": "^1.0",
-                "symfony/console": "^2.7 || ^3.0 || ^4.0",
-                "symfony/filesystem": "^2.7 || ^3.0 || ^4.0",
-                "symfony/finder": "^2.7 || ^3.0 || ^4.0",
-                "symfony/process": "^2.7 || ^3.0 || ^4.0"
+                "symfony/console": "^2.7 || ^3.0 || ^4.0 || ^5.0",
+                "symfony/filesystem": "^2.7 || ^3.0 || ^4.0 || ^5.0",
+                "symfony/finder": "^2.7 || ^3.0 || ^4.0 || ^5.0",
+                "symfony/process": "^2.7 || ^3.0 || ^4.0 || ^5.0"
             },
             "conflict": {
                 "symfony/console": "2.8.38"
             },
             "require-dev": {
-                "phpunit/phpunit": "^4.8.35 || ^5.7",
-                "phpunit/phpunit-mock-objects": "^2.3 || ^3.0"
+                "phpspec/prophecy": "^1.10",
+                "symfony/phpunit-bridge": "^3.4"
             },
             "suggest": {
                 "ext-openssl": "Enabling the openssl extension allows you to access https URLs for repositories and packages",
@@ -480,7 +480,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.9-dev"
+                    "dev-master": "1.10-dev"
                 }
             },
             "autoload": {
@@ -511,7 +511,17 @@
                 "dependency",
                 "package"
             ],
-            "time": "2019-11-01T16:20:17+00:00"
+            "funding": [
+                {
+                    "url": "https://packagist.com",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/composer/composer",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2020-03-10T13:08:05+00:00"
         },
         {
             "name": "composer/semver",
@@ -4577,5 +4587,6 @@
     "platform-dev": [],
     "platform-overrides": {
         "php": "7.1.33"
-    }
+    },
+    "plugin-api-version": "1.1.0"
 }
diff --git a/test/Fixture/json/valid/lock/present/lock/fresh-before/json/already-normalized/composer.lock b/test/Fixture/json/valid/lock/present/lock/fresh-before/json/already-normalized/composer.lock
index fbc47751..0c2504b4 100644
--- a/test/Fixture/json/valid/lock/present/lock/fresh-before/json/already-normalized/composer.lock
+++ b/test/Fixture/json/valid/lock/present/lock/fresh-before/json/already-normalized/composer.lock
@@ -16,5 +16,6 @@
         "php": "^7.1",
         "ext-json": "*"
     },
-    "platform-dev": []
+    "platform-dev": [],
+    "plugin-api-version": "1.1.0"
 }
diff --git a/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/fresh-after/composer.lock b/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/fresh-after/composer.lock
index fbc47751..0c2504b4 100644
--- a/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/fresh-after/composer.lock
+++ b/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/fresh-after/composer.lock
@@ -16,5 +16,6 @@
         "php": "^7.1",
         "ext-json": "*"
     },
-    "platform-dev": []
+    "platform-dev": [],
+    "plugin-api-version": "1.1.0"
 }
diff --git a/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/not-fresh-after/composer.lock b/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/not-fresh-after/composer.lock
index 73c98dbe..6df641a4 100644
--- a/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/not-fresh-after/composer.lock
+++ b/test/Fixture/json/valid/lock/present/lock/fresh-before/json/not-yet-normalized/lock/not-fresh-after/composer.lock
@@ -16,5 +16,6 @@
         "ext-json": "*",
         "php": "^7.1"
     },
-    "platform-dev": []
+    "platform-dev": [],
+    "plugin-api-version": "1.1.0"
 }