diff --git a/wp-admin/includes/class-wp-comments-list-table.php b/wp-admin/includes/class-wp-comments-list-table.php
index da54905b72..f12565a95f 100644
--- a/wp-admin/includes/class-wp-comments-list-table.php
+++ b/wp-admin/includes/class-wp-comments-list-table.php
@@ -33,14 +33,14 @@ class WP_Comments_List_Table extends WP_List_Table {
 	 *
 	 * @see WP_List_Table::__construct() for more information on default arguments.
 	 *
-	 * @global int|bool $post_id
+	 * @global int $post_id
 	 *
 	 * @param array $args An associative array of arguments.
 	 */
 	public function __construct( $args = array() ) {
 		global $post_id;
 
-		$post_id = isset( $_REQUEST['p'] ) ? absint( $_REQUEST['p'] ) : false;
+		$post_id = isset( $_REQUEST['p'] ) ? absint( $_REQUEST['p'] ) : 0;
 
 		if ( get_option( 'show_avatars' ) ) {
 			add_filter( 'comment_author', array( $this, 'floated_admin_avatar' ), 10, 2 );
@@ -69,7 +69,7 @@ class WP_Comments_List_Table extends WP_List_Table {
 
 	/**
 	 *
-	 * @global int|bool $post_id
+	 * @global int    $post_id
 	 * @global string $comment_status
 	 * @global string $search
 	 * @global string $comment_type
@@ -192,7 +192,7 @@ class WP_Comments_List_Table extends WP_List_Table {
 
 	/**
 	 *
-	 * @global int|bool $post_id
+	 * @global int $post_id
 	 * @global string $comment_status
 	 * @global string $comment_type
 	 */
@@ -383,7 +383,7 @@ class WP_Comments_List_Table extends WP_List_Table {
 
 	/**
 	 *
-	 * @global int|bool $post_id
+	 * @global int $post_id
 	 *
 	 * @return array
 	 */
diff --git a/wp-includes/class-wp-comment-query.php b/wp-includes/class-wp-comment-query.php
index df1bbaf2ef..4145d8fd76 100644
--- a/wp-includes/class-wp-comment-query.php
+++ b/wp-includes/class-wp-comment-query.php
@@ -214,7 +214,7 @@ class WP_Comment_Query {
 	 *                                                   Default empty.
 	 *     @type int          $post_ID                   Currently unused.
 	 *     @type int          $post_id                   Limit results to those affiliated with a given post ID.
-	 *                                                   Default null.
+	 *                                                   Default 0.
 	 *     @type array        $post__in                  Array of post IDs to include affiliated comments for.
 	 *                                                   Default empty.
 	 *     @type array        $post__not_in              Array of post IDs to exclude affiliated comments for.
@@ -278,7 +278,7 @@ class WP_Comment_Query {
 			'post_author__in' => '',
 			'post_author__not_in' => '',
 			'post_ID' => '',
-			'post_id' => null,
+			'post_id' => 0,
 			'post__in' => '',
 			'post__not_in' => '',
 			'post_author' => '',
@@ -647,8 +647,9 @@ class WP_Comment_Query {
 			$fields = "$wpdb->comments.comment_ID";
 		}
 
-		if ( strlen( $this->query_vars['post_id'] ) ) {
-			$this->sql_clauses['where']['post_id'] = $wpdb->prepare( 'comment_post_ID = %d', $this->query_vars['post_id'] );
+		$post_id = absint( $this->query_vars['post_id'] );
+		if ( ! empty( $post_id ) ) {
+			$this->sql_clauses['where']['post_id'] = $wpdb->prepare( 'comment_post_ID = %d', $post_id );
 		}
 
 		// Parse comment IDs for an IN clause.
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 18732eddd7..2acde723cf 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.5-alpha-36479';
+$wp_version = '4.5-alpha-36480';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.