diff --git a/wp-includes/vars.php b/wp-includes/vars.php
index 2ac305b95..bfd2a5d33 100644
--- a/wp-includes/vars.php
+++ b/wp-includes/vars.php
@@ -80,13 +80,12 @@ $is_apache = (strpos($_SERVER['SERVER_SOFTWARE'], 'Apache') !== false || strpos(
  * Whether the server software is IIS or something else
  * @global bool $is_IIS
  */
-$is_IIS = (strpos($_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS') !== false || strpos($_SERVER['SERVER_SOFTWARE'], 'ExpressionDevServer') !== false);
+$is_IIS = !$is_apache && (strpos($_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS') !== false || strpos($_SERVER['SERVER_SOFTWARE'], 'ExpressionDevServer') !== false);
 
 /**
  * Whether the server software is IIS 7.X
  * @global bool $is_iis7
  */
-$is_iis7 = (strpos($_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS/7.') !== false);
-
+$is_iis7 = $is_IIS && (strpos($_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS/7.') !== false);
 
 ?>
\ No newline at end of file