diff --git a/src/Command/Extension/SetExtensionVersionCommand.php b/src/Command/Extension/SetExtensionVersionCommand.php
index 8f1ad45..3c7cd1e 100644
--- a/src/Command/Extension/SetExtensionVersionCommand.php
+++ b/src/Command/Extension/SetExtensionVersionCommand.php
@@ -28,6 +28,7 @@
  */
 class SetExtensionVersionCommand extends Command
 {
+    private const COMPOSER_PATTERN = '"version": "([0-9]+\.[0-9]+\.[0-9]+)"';
     private const EMCONF_PATTERN = '["\']version["\']\s=>\s["\']((?:[0-9]+)\.[0-9]+\.[0-9]+\s*)["\']';
 
     // Documentation/guides.xml
@@ -64,6 +65,12 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             return 1;
         }
 
+        $composerFile = rtrim($path, '/') . '/composer.json';
+        if (!file_exists($composerFile)) {
+            $io->error(sprintf('No \'composer.json\' found in the given path %s.', $path));
+            return self::FAILURE;
+        }
+
         $emConfFile = rtrim($path, '/') . '/ext_emconf.php';
         if (!file_exists($emConfFile)) {
             $io->error(sprintf('No \'ext_emconf.php\' found in the given path %s.', $path));
@@ -72,6 +79,13 @@ protected function execute(InputInterface $input, OutputInterface $output): int
 
         $versionReplacer = new VersionReplacer($version);
 
+        try {
+            $versionReplacer->setVersion($composerFile, self::COMPOSER_PATTERN);
+        } catch (\InvalidArgumentException) {
+            $io->error(sprintf('An error occurred while setting the composer.json version to %s.', $version));
+            return self::FAILURE;
+        }
+
         try {
             $versionReplacer->setVersion($emConfFile, self::EMCONF_PATTERN);
         } catch (\InvalidArgumentException $e) {
diff --git a/tests/Unit/Filesystem/VersionReplacerTest.php b/tests/Unit/Filesystem/VersionReplacerTest.php
index 5d6c1bc..c5d58ff 100644
--- a/tests/Unit/Filesystem/VersionReplacerTest.php
+++ b/tests/Unit/Filesystem/VersionReplacerTest.php
@@ -19,6 +19,19 @@
 
 class VersionReplacerTest extends TestCase
 {
+    #[Test]
+    public function replaceVersionReplacesProperVersionOfComposerJson(): void
+    {
+        $composerContents = file_get_contents(__DIR__ . '/../Fixtures/Composer/composer_with_extension_key.json');
+        $tempFile = tempnam('/tmp/', 'tailor_composer.json');
+        file_put_contents($tempFile, $composerContents);
+        $subject = new VersionReplacer('6.9.0');
+        $subject->setVersion($tempFile, '"version": "([0-9]+\.[0-9]+\.[0-9]+)"');
+        $contents = file_get_contents($tempFile);
+        self::assertStringContainsString('"version": "6.9.0"', $contents);
+        unlink($tempFile);
+    }
+
     #[Test]
     public function replaceVersionReplacesProperVersionOfEmConf(): void
     {
diff --git a/tests/Unit/Fixtures/Composer/composer_with_extension_key.json b/tests/Unit/Fixtures/Composer/composer_with_extension_key.json
index e570d26..5a2ffb6 100644
--- a/tests/Unit/Fixtures/Composer/composer_with_extension_key.json
+++ b/tests/Unit/Fixtures/Composer/composer_with_extension_key.json
@@ -19,7 +19,8 @@
   },
   "extra": {
     "typo3/cms": {
-      "extension-key": "my-extension"
+      "extension-key": "my-extension",
+      "version": "1.0.0"
     }
   }
 }