diff --git a/src/wp-includes/general-template.php b/src/wp-includes/general-template.php
index de0f921dab..51cc66bb23 100644
--- a/src/wp-includes/general-template.php
+++ b/src/wp-includes/general-template.php
@@ -2582,20 +2582,18 @@ function language_attributes($doctype = 'html') {
 function paginate_links( $args = '' ) {
 	global $wp_query, $wp_rewrite;
 
-	$total        = ( isset( $wp_query->max_num_pages ) ) ? $wp_query->max_num_pages : 1;
-	$current      = ( get_query_var( 'paged' ) ) ? intval( get_query_var( 'paged' ) ) : 1;
+	// Setting up default values based on the current URL.
 	$pagenum_link = html_entity_decode( get_pagenum_link() );
-	$query_args   = array();
 	$url_parts    = explode( '?', $pagenum_link );
 
-	if ( isset( $url_parts[1] ) ) {
-		wp_parse_str( $url_parts[1], $query_args );
-		$query_args = urlencode_deep( $query_args );
-	}
+	// Get max pages and current page out of the current query, if available.
+	$total   = isset( $wp_query->max_num_pages ) ? $wp_query->max_num_pages : 1;
+	$current = get_query_var( 'paged' ) ? intval( get_query_var( 'paged' ) ) : 1;
 
-	$pagenum_link = remove_query_arg( array_keys( $query_args ), $pagenum_link );
-	$pagenum_link = trailingslashit( $pagenum_link ) . '%_%';
+	// Append the format placeholder to the base URL.
+	$pagenum_link = trailingslashit( $url_parts[0] ) . '%_%';
 
+	// URL base depends on permalink settings.
 	$format  = $wp_rewrite->using_index_permalinks() && ! strpos( $pagenum_link, 'index.php' ) ? 'index.php/' : '';
 	$format .= $wp_rewrite->using_permalinks() ? user_trailingslashit( $wp_rewrite->pagination_base . '/%#%', 'paged' ) : '?paged=%#%';
 
@@ -2611,7 +2609,7 @@ function paginate_links( $args = '' ) {
 		'end_size' => 1,
 		'mid_size' => 2,
 		'type' => 'plain',
-		'add_args' => $query_args, // array of query args to add
+		'add_args' => array(), // array of query args to add
 		'add_fragment' => '',
 		'before_page_number' => '',
 		'after_page_number' => ''
@@ -2619,6 +2617,17 @@ function paginate_links( $args = '' ) {
 
 	$args = wp_parse_args( $args, $defaults );
 
+	// Merge additional query vars found in the original URL into 'add_args' array.
+	if ( isset( $url_parts[1] ) ) {
+		// Find the format argument.
+		$format_query = parse_url( str_replace( '%_%', $args['format'], $args['base'] ), PHP_URL_QUERY );
+		wp_parse_str( $format_query, $format_arg );
+
+		// Remove the format argument from the array of query arguments, to avoid overwriting custom format.
+		wp_parse_str( remove_query_arg( array_keys( $format_arg ), $url_parts[1] ), $query_args );
+		$args['add_args'] = array_merge( $args['add_args'], urlencode_deep( $query_args ) );
+	}
+
 	// Who knows what else people pass in $args
 	$total = (int) $args['total'];
 	if ( $total < 2 ) {
diff --git a/tests/phpunit/tests/general/paginateLinks.php b/tests/phpunit/tests/general/paginateLinks.php
index b2083bbd26..930dcde301 100644
--- a/tests/phpunit/tests/general/paginateLinks.php
+++ b/tests/phpunit/tests/general/paginateLinks.php
@@ -229,4 +229,66 @@ EXPECTED;
 			$this->assertEquals( $expected_href, $href );
 		}
 	}
+
+	/**
+	 * @ticket 30831
+	 */
+	function test_paginate_links_with_custom_query_args() {
+		add_filter( 'get_pagenum_link', array( $this, 'add_query_arg' ) );
+		$links = paginate_links( array(
+			'current'  => 2,
+			'total'    => 5,
+			'end_size' => 1,
+			'mid_size' => 1,
+			'type'     => 'array',
+			'add_args' => array(
+				'baz' => 'qux',
+			),
+		) );
+		remove_filter( 'get_pagenum_link', array( $this, 'add_query_arg' ) );
+
+		$document = new DOMDocument();
+		$document->preserveWhiteSpace = false;
+
+		$data = array(
+			0 => home_url( '/?baz=qux&foo=bar&s=search+term' ),
+			1 => home_url( '/?baz=qux&foo=bar&s=search+term' ),
+			3 => home_url( '/?paged=3&baz=qux&foo=bar&s=search+term' ),
+			5 => home_url( '/?paged=5&baz=qux&foo=bar&s=search+term' ),
+			6 => home_url( '/?paged=3&baz=qux&foo=bar&s=search+term' ),
+		);
+
+		foreach ( $data as $index => $expected_href ) {
+			$document->loadHTML( $links[ $index ] );
+			$tag = $document->getElementsByTagName( 'a' )->item( 0 );
+			$this->assertNotNull( $tag );
+
+			$href = $tag->attributes->getNamedItem( 'href' )->value;
+			$this->assertEquals( $expected_href, $href );
+		}
+	}
+
+	/**
+	 * @ticket 30831
+	 */
+	public function test_paginate_links_should_allow_non_default_format_without_add_args() {
+		// Fake the query params.
+		$request_uri = $_SERVER['REQUEST_URI'];
+		$_SERVER['REQUEST_URI'] = add_query_arg( 'foo', 3, home_url() );
+
+		$links = paginate_links( array(
+			'base'    => add_query_arg( 'foo', '%#%' ),
+			'format'  => '',
+			'total'   => 5,
+			'current' => 3,
+			'type'    => 'array',
+		) );
+
+		$this->assertContains( '?foo=1', $links[1] );
+		$this->assertContains( '?foo=2', $links[2] );
+		$this->assertContains( '?foo=4', $links[4] );
+		$this->assertContains( '?foo=5', $links[5] );
+
+		$_SERVER['REQUEST_URI'] = $request_uri;
+	}
 }