diff --git a/Makefile b/Makefile
index b061cfbb..7317ad50 100644
--- a/Makefile
+++ b/Makefile
@@ -21,8 +21,7 @@ require: ## Run `composer require`
 remove: ## Run `composer remove`
 	docker compose run php$(PHP_VERSION) composer remove $(filter-out $@, $(MAKECMDGOALS))
 
-check: ## Run all checks in succession (phpcs, phpunit, phpstan)
-	cs analyse phpunit
+check: cs analyse phpunit ## Run all checks in succession (phpcs, phpunit, phpstan)
 
 phpunit: ## Run phpunit tests
 	docker compose run php$(PHP_VERSION) vendor/bin/phpunit
diff --git a/src/Console/Command/UnusedCommand.php b/src/Console/Command/UnusedCommand.php
index 1aa8221e..33874f03 100644
--- a/src/Console/Command/UnusedCommand.php
+++ b/src/Console/Command/UnusedCommand.php
@@ -137,7 +137,7 @@ protected function execute(InputInterface $input, OutputInterface $output): int
                     }
 
                     if ($secondRequiredDependency->requires($requiredDependency)) {
-                        // TODO add "required by" in output
+                        $requiredDependency->requiredBy($secondRequiredDependency);
                         $requiredDependency->markUsed();
                         continue 2;
                     }
@@ -178,14 +178,26 @@ static function (DependencyInterface $dependency) {
         $io->newLine();
         $io->text('<fg=green>Used packages</>');
         foreach ($usedDependencyCollection as $usedDependency) {
-            // TODO add required by dependency
+            $requiredBy = '';
             // TODO add suggest by dependency
 
+            if (!empty($usedDependency->getRequiredBy())) {
+                $requiredByNames = array_map(static function (DependencyInterface $dependency) {
+                    return $dependency->getName();
+                }, $usedDependency->getRequiredBy());
+
+                $requiredBy = sprintf(
+                    ' (<fg=cyan>required by: %s</>)',
+                    implode(', ', $requiredByNames)
+                );
+            }
+
             $io->writeln(
                 sprintf(
-                    ' <fg=green>%s</> %s',
+                    ' <fg=green>%s</> %s%s',
                     "\u{2713}",
-                    $usedDependency->getName()
+                    $usedDependency->getName(),
+                    $requiredBy
                 )
             );
         }
diff --git a/src/Dependency/DependencyInterface.php b/src/Dependency/DependencyInterface.php
index 7595ad71..7b6fa4b7 100644
--- a/src/Dependency/DependencyInterface.php
+++ b/src/Dependency/DependencyInterface.php
@@ -21,4 +21,11 @@ public function provides(SymbolInterface $symbol): bool;
     public function requires(DependencyInterface $dependency): bool;
 
     public function suggests(DependencyInterface $dependency): bool;
+
+    public function requiredBy(DependencyInterface $dependency): void;
+
+    /**
+     * @return array<DependencyInterface>
+     */
+    public function getRequiredBy(): array;
 }
diff --git a/src/Dependency/InvalidDependency.php b/src/Dependency/InvalidDependency.php
index f3f0db99..de572a6f 100644
--- a/src/Dependency/InvalidDependency.php
+++ b/src/Dependency/InvalidDependency.php
@@ -49,4 +49,13 @@ public function suggests(DependencyInterface $dependency): bool
     {
         return false;
     }
+
+    public function requiredBy(DependencyInterface $dependency): void
+    {
+    }
+
+    public function getRequiredBy(): array
+    {
+        return [];
+    }
 }
diff --git a/src/Dependency/RequiredDependency.php b/src/Dependency/RequiredDependency.php
index 84734d0f..64b0a250 100644
--- a/src/Dependency/RequiredDependency.php
+++ b/src/Dependency/RequiredDependency.php
@@ -18,6 +18,8 @@ final class RequiredDependency implements DependencyInterface
     private $package;
     /** @var SymbolListInterface */
     private $symbols;
+    /** @var array<DependencyInterface> */
+    private $requiredBy = [];
 
     public function __construct(PackageInterface $package, SymbolListInterface $symbols)
     {
@@ -60,4 +62,14 @@ public function suggests(DependencyInterface $dependency): bool
     {
         return array_key_exists($dependency->getName(), $this->package->getSuggests());
     }
+
+    public function requiredBy(DependencyInterface $dependency): void
+    {
+        $this->requiredBy[$dependency->getName()] = $dependency;
+    }
+
+    public function getRequiredBy(): array
+    {
+        return $this->requiredBy;
+    }
 }
diff --git a/tests/Integration/UnusedCommandTest.php b/tests/Integration/UnusedCommandTest.php
index 0a077467..d987b28b 100644
--- a/tests/Integration/UnusedCommandTest.php
+++ b/tests/Integration/UnusedCommandTest.php
@@ -7,7 +7,6 @@
 use Composer\Composer;
 use Composer\Console\Application;
 use Composer\IO\IOInterface;
-use Icanhazstring\Composer\Unused\Command\UnusedCommandLegacy;
 use Icanhazstring\Composer\Unused\Console\Command\UnusedCommand;
 use Icanhazstring\Composer\Unused\Di\ServiceContainer;
 use PHPUnit\Framework\TestCase;
diff --git a/tests/Unit/Dependency/RequiredDependencyTest.php b/tests/Unit/Dependency/RequiredDependencyTest.php
index 5b790f42..5762bc45 100644
--- a/tests/Unit/Dependency/RequiredDependencyTest.php
+++ b/tests/Unit/Dependency/RequiredDependencyTest.php
@@ -8,7 +8,6 @@
 use Composer\Package\Package;
 use Composer\Package\PackageInterface;
 use Composer\Semver\Constraint\ConstraintInterface;
-use Icanhazstring\Composer\Unused\Dependency\Dependency;
 use Icanhazstring\Composer\Unused\Dependency\RequiredDependency;
 use ComposerUnused\SymbolParser\Symbol\Symbol;
 use ComposerUnused\SymbolParser\Symbol\SymbolList;