diff --git a/.github/workflows/coding-standards.yml b/.github/workflows/coding-standards.yml
new file mode 100644
index 0000000..05e5214
--- /dev/null
+++ b/.github/workflows/coding-standards.yml
@@ -0,0 +1,29 @@
+name: Coding standards
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Validate composer.json and composer.lock
+      run: composer validate
+
+    - name: Cache Composer packages
+      id: composer-cache
+      uses: actions/cache@v2
+      with:
+        path: vendor
+        key: ${{ runner.os }}-node-${{ hashFiles('**/composer.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-node-
+
+    - name: Install dependencies
+      if: steps.composer-cache.outputs.cache-hit != 'true'
+      run: composer install --prefer-dist --no-progress --no-suggest
+
+    - name: Run coding standards checks
+      run: composer test:standards
diff --git a/.github/workflows/unit-tests.yml b/.github/workflows/unit-tests.yml
new file mode 100644
index 0000000..9679e58
--- /dev/null
+++ b/.github/workflows/unit-tests.yml
@@ -0,0 +1,33 @@
+name: Unit tests
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php: [7.0, 7.1, 7.2, 7.3, 7.4]
+      fail-fast: true
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Validate composer.json and composer.lock
+      run: composer validate
+      
+    - name: Cache Composer packages
+      id: composer-cache
+      uses: actions/cache@v2
+      with:
+        path: vendor
+        key: ${{ runner.os }}-node-${{ hashFiles('**/composer.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-node-
+
+    - name: Install dependencies
+      if: steps.composer-cache.outputs.cache-hit != 'true'
+      run: composer install --prefer-dist --no-progress --no-suggest
+
+    - name: Run test suite
+      run: composer test:unit
diff --git a/.phpcs.xml.dist b/.phpcs.xml.dist
new file mode 100644
index 0000000..2a9ca8f
--- /dev/null
+++ b/.phpcs.xml.dist
@@ -0,0 +1,22 @@
+<?xml version="1.0"?>
+<ruleset name="assertwell/phpunit-global-state">
+    <description>Coding standards for assertwell/phpunit-global-state.</description>
+
+    <arg value="sp" />
+    <arg name="basepath" value="./" />
+    <arg name="colors" />
+    <arg name="extensions" value="php" />
+    <arg name="parallel" value="8" />
+
+    <!-- Only scan PHP files that belong to the app. -->
+    <file>src</file>
+    <file>tests</file>
+
+    <!-- Use PSR-12 as a base. -->
+    <rule ref="PSR12" />
+
+    <!-- Test methods may use snake_case. -->
+    <rule ref="PSR1.Methods.CamelCapsMethodName.NotCamelCaps">
+        <exclude-pattern>tests</exclude-pattern>
+    </rule>
+</ruleset>
diff --git a/composer.json b/composer.json
index 4428059..608d022 100644
--- a/composer.json
+++ b/composer.json
@@ -1,6 +1,6 @@
 {
     "name": "assertwell/phpunit-global-state",
-    "description": "Tools for safely manipulating global state in tests",
+    "description": "Tools for testing applications that depend on global state with PHPUnit",
     "keywords": [
         "env",
         "environment variables",
@@ -24,7 +24,12 @@
         "php": ">=7.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.3"
+        "phpunit/phpunit": "^8.3",
+        "squizlabs/php_codesniffer": "^3.5",
+        "stevegrunwell/runkit7-installer": "^1.1"
+    },
+    "suggest": {
+        "stevegrunwell/runkit7-installer": "Streamline installation of Runkit7"
     },
     "autoload": {
         "psr-4": {
@@ -42,11 +47,21 @@
         "optimize-autoloader": true
     },
     "scripts": {
-        "code-coverage": [
+        "test": [
+            "@test:unit"
+        ],
+        "test:coverage": [
             "phpdbg -qrr -d memory_limit=-1 ./vendor/bin/phpunit --colors=always --testdox --coverage-html=tests/coverage"
+        ],
+        "test:standards": [
+            "phpcs"
+        ],
+        "test:unit": [
+            "phpunit --testdox --colors=always"
         ]
     },
     "scripts-descriptions": {
-        "code-coverage": "Generate HTML code coverage reports in tests/coverage/."
+        "test:coverage": "Generate HTML code coverage reports in tests/coverage/.",
+        "test:unit": "Run unit tests for the library."
     }
 }
diff --git a/composer.lock b/composer.lock
index d46b858..9bfe326 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,25 +4,25 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "669a1da4c33e2b4f0c1781008939849b",
+    "content-hash": "f60c45d25d0fd8250bfc4bac3761de30",
     "packages": [],
     "packages-dev": [
         {
             "name": "doctrine/instantiator",
-            "version": "1.2.0",
+            "version": "1.3.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/doctrine/instantiator.git",
-                "reference": "a2c590166b2133a4633738648b6b064edae0814a"
+                "reference": "f350df0268e904597e3bd9c4685c53e0e333feea"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/a2c590166b2133a4633738648b6b064edae0814a",
-                "reference": "a2c590166b2133a4633738648b6b064edae0814a",
+                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/f350df0268e904597e3bd9c4685c53e0e333feea",
+                "reference": "f350df0268e904597e3bd9c4685c53e0e333feea",
                 "shasum": ""
             },
             "require": {
-                "php": "^7.1"
+                "php": "^7.1 || ^8.0"
             },
             "require-dev": {
                 "doctrine/coding-standard": "^6.0",
@@ -61,20 +61,34 @@
                 "constructor",
                 "instantiate"
             ],
-            "time": "2019-03-17T17:37:11+00:00"
+            "funding": [
+                {
+                    "url": "https://www.doctrine-project.org/sponsorship.html",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://www.patreon.com/phpdoctrine",
+                    "type": "patreon"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/doctrine%2Finstantiator",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2020-05-29T17:27:14+00:00"
         },
         {
             "name": "myclabs/deep-copy",
-            "version": "1.9.3",
+            "version": "1.9.5",
             "source": {
                 "type": "git",
                 "url": "https://github.com/myclabs/DeepCopy.git",
-                "reference": "007c053ae6f31bba39dfa19a7726f56e9763bbea"
+                "reference": "b2c28789e80a97badd14145fda39b545d83ca3ef"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/007c053ae6f31bba39dfa19a7726f56e9763bbea",
-                "reference": "007c053ae6f31bba39dfa19a7726f56e9763bbea",
+                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/b2c28789e80a97badd14145fda39b545d83ca3ef",
+                "reference": "b2c28789e80a97badd14145fda39b545d83ca3ef",
                 "shasum": ""
             },
             "require": {
@@ -109,7 +123,7 @@
                 "object",
                 "object graph"
             ],
-            "time": "2019-08-09T12:45:53+00:00"
+            "time": "2020-01-17T21:11:47+00:00"
         },
         {
             "name": "phar-io/manifest",
@@ -215,24 +229,21 @@
         },
         {
             "name": "phpdocumentor/reflection-common",
-            "version": "2.0.0",
+            "version": "2.1.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionCommon.git",
-                "reference": "63a995caa1ca9e5590304cd845c15ad6d482a62a"
+                "reference": "6568f4687e5b41b054365f9ae03fcb1ed5f2069b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionCommon/zipball/63a995caa1ca9e5590304cd845c15ad6d482a62a",
-                "reference": "63a995caa1ca9e5590304cd845c15ad6d482a62a",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionCommon/zipball/6568f4687e5b41b054365f9ae03fcb1ed5f2069b",
+                "reference": "6568f4687e5b41b054365f9ae03fcb1ed5f2069b",
                 "shasum": ""
             },
             "require": {
                 "php": ">=7.1"
             },
-            "require-dev": {
-                "phpunit/phpunit": "~6"
-            },
             "type": "library",
             "extra": {
                 "branch-alias": {
@@ -263,44 +274,42 @@
                 "reflection",
                 "static analysis"
             ],
-            "time": "2018-08-07T13:53:10+00:00"
+            "time": "2020-04-27T09:25:28+00:00"
         },
         {
             "name": "phpdocumentor/reflection-docblock",
-            "version": "4.3.2",
+            "version": "5.1.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionDocBlock.git",
-                "reference": "b83ff7cfcfee7827e1e78b637a5904fe6a96698e"
+                "reference": "cd72d394ca794d3466a3b2fc09d5a6c1dc86b47e"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/b83ff7cfcfee7827e1e78b637a5904fe6a96698e",
-                "reference": "b83ff7cfcfee7827e1e78b637a5904fe6a96698e",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/cd72d394ca794d3466a3b2fc09d5a6c1dc86b47e",
+                "reference": "cd72d394ca794d3466a3b2fc09d5a6c1dc86b47e",
                 "shasum": ""
             },
             "require": {
-                "php": "^7.0",
-                "phpdocumentor/reflection-common": "^1.0.0 || ^2.0.0",
-                "phpdocumentor/type-resolver": "~0.4 || ^1.0.0",
-                "webmozart/assert": "^1.0"
+                "ext-filter": "^7.1",
+                "php": "^7.2",
+                "phpdocumentor/reflection-common": "^2.0",
+                "phpdocumentor/type-resolver": "^1.0",
+                "webmozart/assert": "^1"
             },
             "require-dev": {
-                "doctrine/instantiator": "^1.0.5",
-                "mockery/mockery": "^1.0",
-                "phpunit/phpunit": "^6.4"
+                "doctrine/instantiator": "^1",
+                "mockery/mockery": "^1"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "4.x-dev"
+                    "dev-master": "5.x-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
-                    "phpDocumentor\\Reflection\\": [
-                        "src/"
-                    ]
+                    "phpDocumentor\\Reflection\\": "src"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -311,33 +320,36 @@
                 {
                     "name": "Mike van Riel",
                     "email": "me@mikevanriel.com"
+                },
+                {
+                    "name": "Jaap van Otterdijk",
+                    "email": "account@ijaap.nl"
                 }
             ],
             "description": "With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.",
-            "time": "2019-09-12T14:27:41+00:00"
+            "time": "2020-02-22T12:28:44+00:00"
         },
         {
             "name": "phpdocumentor/type-resolver",
-            "version": "1.0.1",
+            "version": "1.1.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/TypeResolver.git",
-                "reference": "2e32a6d48972b2c1976ed5d8967145b6cec4a4a9"
+                "reference": "7462d5f123dfc080dfdf26897032a6513644fc95"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/TypeResolver/zipball/2e32a6d48972b2c1976ed5d8967145b6cec4a4a9",
-                "reference": "2e32a6d48972b2c1976ed5d8967145b6cec4a4a9",
+                "url": "https://api.github.com/repos/phpDocumentor/TypeResolver/zipball/7462d5f123dfc080dfdf26897032a6513644fc95",
+                "reference": "7462d5f123dfc080dfdf26897032a6513644fc95",
                 "shasum": ""
             },
             "require": {
-                "php": "^7.1",
+                "php": "^7.2",
                 "phpdocumentor/reflection-common": "^2.0"
             },
             "require-dev": {
-                "ext-tokenizer": "^7.1",
-                "mockery/mockery": "~1",
-                "phpunit/phpunit": "^7.0"
+                "ext-tokenizer": "^7.2",
+                "mockery/mockery": "~1"
             },
             "type": "library",
             "extra": {
@@ -361,37 +373,37 @@
                 }
             ],
             "description": "A PSR-5 based resolver of Class names, Types and Structural Element Names",
-            "time": "2019-08-22T18:11:29+00:00"
+            "time": "2020-02-18T18:59:58+00:00"
         },
         {
             "name": "phpspec/prophecy",
-            "version": "1.8.1",
+            "version": "v1.10.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpspec/prophecy.git",
-                "reference": "1927e75f4ed19131ec9bcc3b002e07fb1173ee76"
+                "reference": "451c3cd1418cf640de218914901e51b064abb093"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/1927e75f4ed19131ec9bcc3b002e07fb1173ee76",
-                "reference": "1927e75f4ed19131ec9bcc3b002e07fb1173ee76",
+                "url": "https://api.github.com/repos/phpspec/prophecy/zipball/451c3cd1418cf640de218914901e51b064abb093",
+                "reference": "451c3cd1418cf640de218914901e51b064abb093",
                 "shasum": ""
             },
             "require": {
                 "doctrine/instantiator": "^1.0.2",
                 "php": "^5.3|^7.0",
-                "phpdocumentor/reflection-docblock": "^2.0|^3.0.2|^4.0",
-                "sebastian/comparator": "^1.1|^2.0|^3.0",
-                "sebastian/recursion-context": "^1.0|^2.0|^3.0"
+                "phpdocumentor/reflection-docblock": "^2.0|^3.0.2|^4.0|^5.0",
+                "sebastian/comparator": "^1.2.3|^2.0|^3.0|^4.0",
+                "sebastian/recursion-context": "^1.0|^2.0|^3.0|^4.0"
             },
             "require-dev": {
-                "phpspec/phpspec": "^2.5|^3.2",
+                "phpspec/phpspec": "^2.5 || ^3.2",
                 "phpunit/phpunit": "^4.8.35 || ^5.7 || ^6.5 || ^7.1"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.8.x-dev"
+                    "dev-master": "1.10.x-dev"
                 }
             },
             "autoload": {
@@ -424,20 +436,20 @@
                 "spy",
                 "stub"
             ],
-            "time": "2019-06-13T12:50:23+00:00"
+            "time": "2020-03-05T15:02:03+00:00"
         },
         {
             "name": "phpunit/php-code-coverage",
-            "version": "7.0.8",
+            "version": "7.0.10",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/php-code-coverage.git",
-                "reference": "aa0d179a13284c7420fc281fc32750e6cc7c9e2f"
+                "reference": "f1884187926fbb755a9aaf0b3836ad3165b478bf"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/aa0d179a13284c7420fc281fc32750e6cc7c9e2f",
-                "reference": "aa0d179a13284c7420fc281fc32750e6cc7c9e2f",
+                "url": "https://api.github.com/repos/sebastianbergmann/php-code-coverage/zipball/f1884187926fbb755a9aaf0b3836ad3165b478bf",
+                "reference": "f1884187926fbb755a9aaf0b3836ad3165b478bf",
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             },
             "require": {
@@ -487,7 +499,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2019-09-17T06:24:36+00:00"
+            "time": "2019-11-20T13:55:58+00:00"
         },
         {
             "name": "phpunit/php-file-iterator",
@@ -680,16 +692,16 @@
         },
         {
             "name": "phpunit/phpunit",
-            "version": "8.3.5",
+            "version": "8.5.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "302faed7059fde575cf3403a78c730c5e3a62750"
+                "reference": "3f9c4079d1407cd84c51c02c6ad1df6ec2ed1348"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/302faed7059fde575cf3403a78c730c5e3a62750",
-                "reference": "302faed7059fde575cf3403a78c730c5e3a62750",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/3f9c4079d1407cd84c51c02c6ad1df6ec2ed1348",
+                "reference": "3f9c4079d1407cd84c51c02c6ad1df6ec2ed1348",
                 "shasum": ""
             },
             "require": {
@@ -733,7 +745,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "8.3-dev"
+                    "dev-master": "8.5-dev"
                 }
             },
             "autoload": {
@@ -759,7 +771,17 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2019-09-14T09:12:03+00:00"
+            "funding": [
+                {
+                    "url": "https://phpunit.de/donate.html",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/sebastianbergmann",
+                    "type": "github"
+                }
+            ],
+            "time": "2020-06-15T10:45:47+00:00"
         },
         {
             "name": "sebastian/code-unit-reverse-lookup",
@@ -928,16 +950,16 @@
         },
         {
             "name": "sebastian/environment",
-            "version": "4.2.2",
+            "version": "4.2.3",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/environment.git",
-                "reference": "f2a2c8e1c97c11ace607a7a667d73d47c19fe404"
+                "reference": "464c90d7bdf5ad4e8a6aea15c091fec0603d4368"
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             "dist": {
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-                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/f2a2c8e1c97c11ace607a7a667d73d47c19fe404",
-                "reference": "f2a2c8e1c97c11ace607a7a667d73d47c19fe404",
+                "url": "https://api.github.com/repos/sebastianbergmann/environment/zipball/464c90d7bdf5ad4e8a6aea15c091fec0603d4368",
+                "reference": "464c90d7bdf5ad4e8a6aea15c091fec0603d4368",
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             },
             "require": {
@@ -977,7 +999,7 @@
                 "environment",
                 "hhvm"
             ],
-            "time": "2019-05-05T09:05:15+00:00"
+            "time": "2019-11-20T08:46:58+00:00"
         },
         {
             "name": "sebastian/exporter",
@@ -1376,18 +1398,109 @@
             "homepage": "https://github.com/sebastianbergmann/version",
             "time": "2016-10-03T07:35:21+00:00"
         },
+        {
+            "name": "squizlabs/php_codesniffer",
+            "version": "3.5.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/squizlabs/PHP_CodeSniffer.git",
+                "reference": "73e2e7f57d958e7228fce50dc0c61f58f017f9f6"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/squizlabs/PHP_CodeSniffer/zipball/73e2e7f57d958e7228fce50dc0c61f58f017f9f6",
+                "reference": "73e2e7f57d958e7228fce50dc0c61f58f017f9f6",
+                "shasum": ""
+            },
+            "require": {
+                "ext-simplexml": "*",
+                "ext-tokenizer": "*",
+                "ext-xmlwriter": "*",
+                "php": ">=5.4.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.0 || ^5.0 || ^6.0 || ^7.0"
+            },
+            "bin": [
+                "bin/phpcs",
+                "bin/phpcbf"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.x-dev"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Greg Sherwood",
+                    "role": "lead"
+                }
+            ],
+            "description": "PHP_CodeSniffer tokenizes PHP, JavaScript and CSS files and detects violations of a defined set of coding standards.",
+            "homepage": "https://github.com/squizlabs/PHP_CodeSniffer",
+            "keywords": [
+                "phpcs",
+                "standards"
+            ],
+            "time": "2020-04-17T01:09:41+00:00"
+        },
+        {
+            "name": "stevegrunwell/runkit7-installer",
+            "version": "v1.1.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/stevegrunwell/runkit7-installer.git",
+                "reference": "76c4cdaf6a03298a545012f1b8d2588c34a10d0e"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/stevegrunwell/runkit7-installer/zipball/76c4cdaf6a03298a545012f1b8d2588c34a10d0e",
+                "reference": "76c4cdaf6a03298a545012f1b8d2588c34a10d0e",
+                "shasum": ""
+            },
+            "require-dev": {
+                "php": "^7.1",
+                "phpunit/phpunit": ">=6.0"
+            },
+            "bin": [
+                "bin/install-runkit.sh"
+            ],
+            "type": "library",
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Steve Grunwell",
+                    "email": "steve@stevegrunwell.com",
+                    "homepage": "https://stevegrunwell.com"
+                }
+            ],
+            "description": "Installer for PHP Runkit7",
+            "keywords": [
+                "runkit",
+                "testing"
+            ],
+            "time": "2018-12-05T19:16:14+00:00"
+        },
         {
             "name": "symfony/polyfill-ctype",
-            "version": "v1.12.0",
+            "version": "v1.17.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/polyfill-ctype.git",
-                "reference": "550ebaac289296ce228a706d0867afc34687e3f4"
+                "reference": "e94c8b1bbe2bc77507a1056cdb06451c75b427f9"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-ctype/zipball/550ebaac289296ce228a706d0867afc34687e3f4",
-                "reference": "550ebaac289296ce228a706d0867afc34687e3f4",
+                "url": "https://api.github.com/repos/symfony/polyfill-ctype/zipball/e94c8b1bbe2bc77507a1056cdb06451c75b427f9",
+                "reference": "e94c8b1bbe2bc77507a1056cdb06451c75b427f9",
                 "shasum": ""
             },
             "require": {
@@ -1399,7 +1512,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.12-dev"
+                    "dev-master": "1.17-dev"
                 }
             },
             "autoload": {
@@ -1432,7 +1545,21 @@
                 "polyfill",
                 "portable"
             ],
-            "time": "2019-08-06T08:03:45+00:00"
+            "funding": [
+                {
+                    "url": "https://symfony.com/sponsor",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/fabpot",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/symfony/symfony",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2020-05-12T16:14:59+00:00"
         },
         {
             "name": "theseer/tokenizer",
@@ -1476,31 +1603,29 @@
         },
         {
             "name": "webmozart/assert",
-            "version": "1.5.0",
+            "version": "1.8.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/webmozart/assert.git",
-                "reference": "88e6d84706d09a236046d686bbea96f07b3a34f4"
+                "reference": "ab2cb0b3b559010b75981b1bdce728da3ee90ad6"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/webmozart/assert/zipball/88e6d84706d09a236046d686bbea96f07b3a34f4",
-                "reference": "88e6d84706d09a236046d686bbea96f07b3a34f4",
+                "url": "https://api.github.com/repos/webmozart/assert/zipball/ab2cb0b3b559010b75981b1bdce728da3ee90ad6",
+                "reference": "ab2cb0b3b559010b75981b1bdce728da3ee90ad6",
                 "shasum": ""
             },
             "require": {
                 "php": "^5.3.3 || ^7.0",
                 "symfony/polyfill-ctype": "^1.8"
             },
+            "conflict": {
+                "vimeo/psalm": "<3.9.1"
+            },
             "require-dev": {
                 "phpunit/phpunit": "^4.8.36 || ^7.5.13"
             },
             "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.3-dev"
-                }
-            },
             "autoload": {
                 "psr-4": {
                     "Webmozart\\Assert\\": "src/"
@@ -1522,7 +1647,7 @@
                 "check",
                 "validate"
             ],
-            "time": "2019-08-24T08:43:50+00:00"
+            "time": "2020-04-18T12:12:48+00:00"
         }
     ],
     "aliases": [],
@@ -1530,9 +1655,9 @@
     "stability-flags": [],
     "prefer-stable": false,
     "prefer-lowest": false,
-    "platform": [],
+    "platform": {
+        "php": ">=7.0"
+    },
     "platform-dev": [],
-    "platform-overrides": {
-        "php": "7.2"
-    }
+    "plugin-api-version": "1.1.0"
 }
diff --git a/src/GlobalVariables.php b/src/GlobalVariables.php
index 93948e5..0c578de 100644
--- a/src/GlobalVariables.php
+++ b/src/GlobalVariables.php
@@ -47,7 +47,7 @@ protected function setGlobalVariable(string $variable, $value): void
     {
         if (! isset($GLOBALS[$variable])) {
             $this->globalVariables['created'][] = $variable;
-        } elseif (! isset( $this->backedUpGlobals['updated'][$variable])) {
+        } elseif (! isset($this->backedUpGlobals['updated'][$variable])) {
             $this->globalVariables['updated'][$variable] = $GLOBALS[$variable];
         }