diff --git a/src/Symfony/Component/Console/Completion/CompletionInput.php b/src/Symfony/Component/Console/Completion/CompletionInput.php
index df9170528f38..f2c6f5c9c72f 100644
--- a/src/Symfony/Component/Console/Completion/CompletionInput.php
+++ b/src/Symfony/Component/Console/Completion/CompletionInput.php
@@ -117,7 +117,11 @@ public function bind(InputDefinition $definition): void
             }
 
             $this->completionName = $argumentName;
-            $this->completionValue = \is_array($argumentValue ?? '') ? $argumentValue[array_key_last($argumentValue)] : $argumentValue;
+            if (\is_array($argumentValue)) {
+                $this->completionValue = $argumentValue ? $argumentValue[array_key_last($argumentValue)] : null;
+            } else {
+                $this->completionValue = $argumentValue;
+            }
         }
 
         if ($this->currentIndex >= \count($this->tokens)) {
diff --git a/src/Symfony/Component/Console/Tests/Completion/CompletionInputTest.php b/src/Symfony/Component/Console/Tests/Completion/CompletionInputTest.php
index 35470e15404f..4c9251abd652 100644
--- a/src/Symfony/Component/Console/Tests/Completion/CompletionInputTest.php
+++ b/src/Symfony/Component/Console/Tests/Completion/CompletionInputTest.php
@@ -92,6 +92,7 @@ public function testBindWithLastArrayArgument(CompletionInput $input, ?string $e
 
     public function provideBindWithLastArrayArgumentData()
     {
+        yield [CompletionInput::fromTokens(['bin/console'], 1), null];
         yield [CompletionInput::fromTokens(['bin/console', 'symfony', 'sensiolabs'], 3), null];
         yield [CompletionInput::fromTokens(['bin/console', 'symfony', 'sen'], 2), 'sen'];
     }