diff --git a/wp-includes/category-template.php b/wp-includes/category-template.php
index 94753a1dc7..452930bcd5 100644
--- a/wp-includes/category-template.php
+++ b/wp-includes/category-template.php
@@ -677,7 +677,7 @@ function wp_generate_tag_cloud( $tags, $args = '' ) {
 		$tag_link = '#' != $tag->link ? esc_url( $tag->link ) : '#';
 		$tag_id = isset($tags[ $key ]->id) ? $tags[ $key ]->id : $key;
 		$tag_name = $tags[ $key ]->name;
-		$a[] = "<a href='$tag_link' class='tag-link-$tag_id' title='" . esc_attr( call_user_func( 'topic_count_text_callback', $real_count ) ) . "' style='font-size: " .
+		$a[] = "<a href='$tag_link' class='tag-link-$tag_id' title='" . esc_attr( call_user_func( $topic_count_text_callback, $real_count ) ) . "' style='font-size: " .
 			( $smallest + ( ( $count - $min_count ) * $font_step ) )
 			. "$unit;'>$tag_name</a>";
 	}