diff --git a/src/Util/YamlSourceManipulator.php b/src/Util/YamlSourceManipulator.php
index 0a35e9186..7db572a34 100644
--- a/src/Util/YamlSourceManipulator.php
+++ b/src/Util/YamlSourceManipulator.php
@@ -544,7 +544,15 @@ private function advanceBeyondMultilineArrayLastItem(): void
         }
 
         $nextLineBreak = $this->findNextLineBreak($this->currentPosition);
-        if ('}' === trim(substr($this->contents, $this->currentPosition, $nextLineBreak - $this->currentPosition))) {
+        if (false === $nextLineBreak) {
+            $this->log('The last line, going to EOL');
+            $this->advanceToEndOfLine();
+
+            return;
+        }
+
+        $lastSymbolBeforeLineBreak = trim(substr($this->contents, $this->currentPosition, $nextLineBreak - $this->currentPosition));
+        if (\in_array($lastSymbolBeforeLineBreak, ['}', ']'], true)) {
             $this->log('The line ends with an array closing brace, going to EOL');
             $this->advanceToEndOfLine();
         }
diff --git a/tests/Util/yaml_fixtures/add_item_to_array_after_array.test b/tests/Util/yaml_fixtures/add_item_to_array_after_array.test
new file mode 100644
index 000000000..302117272
--- /dev/null
+++ b/tests/Util/yaml_fixtures/add_item_to_array_after_array.test
@@ -0,0 +1,12 @@
+framework:
+    messenger:
+        routing:
+            App\Messages\OldMessage: [ transport1, transport2 ]
+===
+$data['framework']['messenger']['routing']['App\Messages\NewMessage'] = 'async';
+===
+framework:
+    messenger:
+        routing:
+            App\Messages\OldMessage: [ transport1, transport2 ]
+            App\Messages\NewMessage: async
\ No newline at end of file
diff --git a/tests/Util/yaml_fixtures/add_item_to_array_after_array_trailing_newline.test b/tests/Util/yaml_fixtures/add_item_to_array_after_array_trailing_newline.test
new file mode 100644
index 000000000..c7e153d05
--- /dev/null
+++ b/tests/Util/yaml_fixtures/add_item_to_array_after_array_trailing_newline.test
@@ -0,0 +1,13 @@
+framework:
+    messenger:
+        routing:
+            App\Messages\OldMessage: [ transport1, transport2 ]
+
+===
+$data['framework']['messenger']['routing']['App\Messages\NewMessage'] = 'async';
+===
+framework:
+    messenger:
+        routing:
+            App\Messages\OldMessage: [ transport1, transport2 ]
+            App\Messages\NewMessage: async