diff --git a/src/Composer/Command/ConfigCommand.php b/src/Composer/Command/ConfigCommand.php
index 390cf2969..e893e7983 100644
--- a/src/Composer/Command/ConfigCommand.php
+++ b/src/Composer/Command/ConfigCommand.php
@@ -634,11 +634,6 @@ EOT
         if ($input->getOption('global') && (isset($uniqueProps[$settingKey]) || isset($multiProps[$settingKey]) || strpos($settingKey, 'extra.') === 0)) {
             throw new \InvalidArgumentException('The ' . $settingKey . ' property can not be set in the global config.json file. Use `composer global config` to apply changes to the global composer.json');
         }
-        if ($input->getOption('unset') && (isset($uniqueProps[$settingKey]) || isset($multiProps[$settingKey]))) {
-            $this->configSource->removeProperty($settingKey);
-
-            return 0;
-        }
         if (isset($uniqueProps[$settingKey])) {
             $this->handleSingleValue($settingKey, $uniqueProps[$settingKey], $values, 'addProperty');
 
@@ -801,6 +796,12 @@ EOT
             return 0;
         }
 
+        if ($input->getOption('unset')) {
+            $this->configSource->removeProperty($settingKey);
+
+            return 0;
+        }
+
         throw new \InvalidArgumentException('Setting '.$settingKey.' does not exist or is not supported by this command');
     }