diff --git a/Completion/CompletionInput.php b/Completion/CompletionInput.php
index eda95bef5..368b94507 100644
--- a/Completion/CompletionInput.php
+++ b/Completion/CompletionInput.php
@@ -109,12 +109,12 @@ public function bind(InputDefinition $definition): void
         // complete argument value
         $this->completionType = self::TYPE_ARGUMENT_VALUE;
 
-        $arguments = $this->getArguments();
-        foreach ($arguments as $argumentName => $argumentValue) {
-            if (null === $argumentValue) {
+        foreach ($this->definition->getArguments() as $argumentName => $argument) {
+            if (!isset($this->arguments[$argumentName])) {
                 break;
             }
 
+            $argumentValue = $this->arguments[$argumentName];
             $this->completionName = $argumentName;
             if (\is_array($argumentValue)) {
                 $this->completionValue = $argumentValue ? $argumentValue[array_key_last($argumentValue)] : null;
@@ -124,7 +124,7 @@ public function bind(InputDefinition $definition): void
         }
 
         if ($this->currentIndex >= \count($this->tokens)) {
-            if (null === $arguments[$argumentName] || $this->definition->getArgument($argumentName)->isArray()) {
+            if (!isset($this->arguments[$argumentName]) || $this->definition->getArgument($argumentName)->isArray()) {
                 $this->completionName = $argumentName;
                 $this->completionValue = '';
             } else {
diff --git a/Helper/ProcessHelper.php b/Helper/ProcessHelper.php
index 87d3e6539..4ea3d724d 100644
--- a/Helper/ProcessHelper.php
+++ b/Helper/ProcessHelper.php
@@ -31,8 +31,6 @@ class ProcessHelper extends Helper
      * @param array|Process $cmd      An instance of Process or an array of the command and arguments
      * @param callable|null $callback A PHP callback to run whenever there is some
      *                                output available on STDOUT or STDERR
-     *
-     * @return Process
      */
     public function run(OutputInterface $output, $cmd, string $error = null, callable $callback = null, int $verbosity = OutputInterface::VERBOSITY_VERY_VERBOSE): Process
     {
@@ -96,8 +94,6 @@ public function run(OutputInterface $output, $cmd, string $error = null, callabl
      * @param callable|null $callback A PHP callback to run whenever there is some
      *                                output available on STDOUT or STDERR
      *
-     * @return Process
-     *
      * @throws ProcessFailedException
      *
      * @see run()
diff --git a/Tests/ApplicationTest.php b/Tests/ApplicationTest.php
index 9f9620739..fe1f27fcc 100644
--- a/Tests/ApplicationTest.php
+++ b/Tests/ApplicationTest.php
@@ -883,6 +883,9 @@ public function testRenderExceptionLineBreaks()
         $this->assertStringMatchesFormatFile(self::$fixturesPath.'/application_renderexception_linebreaks.txt', $tester->getDisplay(true), '->renderException() keep multiple line breaks');
     }
 
+    /**
+     * @group transient-on-windows
+     */
     public function testRenderAnonymousException()
     {
         $application = new Application();
@@ -906,6 +909,9 @@ public function testRenderAnonymousException()
         $this->assertStringContainsString('Dummy type "class@anonymous" is invalid.', $tester->getDisplay(true));
     }
 
+    /**
+     * @group transient-on-windows
+     */
     public function testRenderExceptionStackTraceContainsRootException()
     {
         $application = new Application();
diff --git a/Tests/Command/HelpCommandTest.php b/Tests/Command/HelpCommandTest.php
index bf0ab9720..0e8a7f4f7 100644
--- a/Tests/Command/HelpCommandTest.php
+++ b/Tests/Command/HelpCommandTest.php
@@ -92,7 +92,7 @@ public function provideCompletionSuggestions()
 
         yield 'nothing' => [
             [''],
-            [],
+            ['completion', 'help', 'list', 'foo:bar'],
         ];
 
         yield 'command_name' => [
diff --git a/Tests/Completion/CompletionInputTest.php b/Tests/Completion/CompletionInputTest.php
index f83a0f898..ee370076c 100644
--- a/Tests/Completion/CompletionInputTest.php
+++ b/Tests/Completion/CompletionInputTest.php
@@ -97,6 +97,20 @@ public function provideBindWithLastArrayArgumentData()
         yield [CompletionInput::fromTokens(['bin/console', 'symfony', 'sen'], 2), 'sen'];
     }
 
+    public function testBindArgumentWithDefault()
+    {
+        $definition = new InputDefinition([
+            new InputArgument('arg-with-default', InputArgument::OPTIONAL, '', 'default'),
+        ]);
+
+        $input = CompletionInput::fromTokens(['bin/console'], 1);
+        $input->bind($definition);
+
+        $this->assertEquals(CompletionInput::TYPE_ARGUMENT_VALUE, $input->getCompletionType(), 'Unexpected type');
+        $this->assertEquals('arg-with-default', $input->getCompletionName(), 'Unexpected name');
+        $this->assertEquals('', $input->getCompletionValue(), 'Unexpected value');
+    }
+
     /**
      * @dataProvider provideFromStringData
      */