diff --git a/includes/TitleArray.php b/includes/TitleArray.php
index 90fb861a94d..cc130d253bb 100644
--- a/includes/TitleArray.php
+++ b/includes/TitleArray.php
@@ -56,7 +56,7 @@ abstract class TitleArray implements Iterator {
 	}
 }
 
-class TitleArrayFromResult extends TitleArray {
+class TitleArrayFromResult extends TitleArray implements Countable {
 
 	/**
 	 * @var ResultWrapper
diff --git a/includes/UserArray.php b/includes/UserArray.php
index 1f55ef35528..12b779e018d 100644
--- a/includes/UserArray.php
+++ b/includes/UserArray.php
@@ -61,7 +61,7 @@ abstract class UserArray implements Iterator {
 	}
 }
 
-class UserArrayFromResult extends UserArray {
+class UserArrayFromResult extends UserArray implements Countable {
 
 	/**
 	 * @var ResultWrapper