diff --git a/src/Symfony/Component/Console/Input/ArrayInput.php b/src/Symfony/Component/Console/Input/ArrayInput.php
index a04b6b68ea0c..b2ebc7c2258e 100644
--- a/src/Symfony/Component/Console/Input/ArrayInput.php
+++ b/src/Symfony/Component/Console/Input/ArrayInput.php
@@ -39,8 +39,8 @@ public function __construct(array $parameters, InputDefinition $definition = nul
      */
     public function getFirstArgument()
     {
-        foreach ($this->parameters as $key => $value) {
-            if ($key && '-' === $key[0]) {
+        foreach ($this->parameters as $param => $value) {
+            if ($param && \is_string($param) && '-' === $param[0]) {
                 continue;
             }
 
@@ -107,7 +107,7 @@ public function __toString()
     {
         $params = [];
         foreach ($this->parameters as $param => $val) {
-            if ($param && '-' === $param[0]) {
+            if ($param && \is_string($param) && '-' === $param[0]) {
                 if (\is_array($val)) {
                     foreach ($val as $v) {
                         $params[] = $param.('' != $v ? '='.$this->escapeToken($v) : '');