diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 29b90af..9ac7192 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -33,4 +33,10 @@ jobs:
           php-version: ${{ matrix.php }}
           coverage: xdebug
       - run: composer install
-      - run: vendor/bin/phpunit --coverage-text ${{ matrix.php < 7.3 && '-c phpunit.xml.legacy' || '' }}
+      - run: vendor/bin/phpunit --coverage-text --coverage-clover clover.xml ${{ matrix.php < 7.3 && '-c phpunit.xml.legacy' || '' }}
+      - name: Check 100% code coverage
+        shell: php {0}
+        run: |
+          <?php
+          $metrics = simplexml_load_file('clover.xml')->project->metrics;
+          exit((int) $metrics['statements'] === (int) $metrics['coveredstatements'] ? 0 : 1);
diff --git a/README.md b/README.md
index 38f7174..d3be434 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # clue/reactphp-tar
 
 [![CI status](https://github.com/clue/reactphp-tar/actions/workflows/ci.yml/badge.svg)](https://github.com/clue/reactphp-tar/actions)
+[![code coverage](https://img.shields.io/badge/code%20coverage-100%25-success)](#tests)
 [![installs on Packagist](https://img.shields.io/packagist/dt/clue/tar-react?color=blue&label=installs%20on%20Packagist)](https://packagist.org/packages/clue/tar-react)
 
 Streaming parser to extract tarballs with [ReactPHP](https://reactphp.org/).
@@ -82,6 +83,14 @@ To run the test suite, go to the project root and run:
 vendor/bin/phpunit
 ```
 
+The test suite is set up to always ensure 100% code coverage across all
+supported environments. If you have the Xdebug extension installed, you can also
+generate a code coverage report locally like this:
+
+```bash
+XDEBUG_MODE=coverage vendor/bin/phpunit --coverage-text
+```
+
 ## License
 
 This project is released under the permissive [MIT license](LICENSE).
diff --git a/src/TarDecoder.php b/src/TarDecoder.php
index d944bd1..9254c6d 100644
--- a/src/TarDecoder.php
+++ b/src/TarDecoder.php
@@ -35,10 +35,12 @@ public function __construct()
     {
         $this->format = "Z100name/Z8mode/Z8uid/Z8gid/Z12size/Z12mtime/Z8checksum/Z1type/Z100symlink/Z6magic/Z2version/Z32owner/Z32group/Z8deviceMajor/Z8deviceMinor/Z155prefix/Z12unpacked";
 
+        // @codeCoverageIgnoreStart
         if (PHP_VERSION < 5.5) {
             // PHP 5.5 replaced 'a' with 'Z' (read X bytes and removing trailing NULL bytes)
-            $this->format = str_replace('Z', 'a', $this->format); // @codeCoverageIgnore
+            $this->format = str_replace('Z', 'a', $this->format);
         }
+        // @codeCoverageIgnoreEnd
     }
 
     public function write($data)