Index: src/wp-includes/link-template.php
===================================================================
--- src/wp-includes/link-template.php	(revision 27690)
+++ src/wp-includes/link-template.php	(working copy)
@@ -1293,7 +1293,7 @@
 		$query_args = array(
 			'posts_per_page'      => 1,
 			'post_status'         => 'publish',
-			'post_type'           => 'post',
+			'post_type'           => $this->current_post->post_type,
 			'orderby'             => 'date',
 			'order'               => 'previous' === $this->adjacent ? 'DESC' : 'ASC',
 			'ignore_sticky_posts' => true,
Index: tests/phpunit/tests/link.php
===================================================================
--- tests/phpunit/tests/link.php	(revision 27690)
+++ tests/phpunit/tests/link.php	(working copy)
@@ -175,24 +175,37 @@
 		// Need some sample posts to test adjacency
 		$post_one = $this->factory->post->create_and_get( array(
 			'post_title' => 'First',
-			'post_date' => '2012-01-01 12:00:00'
+			'post_date'  => '2012-01-01 12:00:00',
 		) );
 
 		$post_two = $this->factory->post->create_and_get( array(
 			'post_title' => 'Second',
-			'post_date' => '2012-02-01 12:00:00'
+			'post_date'  => '2012-02-01 12:00:00',
 		) );
 
 		$post_three = $this->factory->post->create_and_get( array(
 			'post_title' => 'Third',
-			'post_date' => '2012-03-01 12:00:00'
+			'post_date'  => '2012-03-01 12:00:00',
 		) );
 
 		$post_four = $this->factory->post->create_and_get( array(
 			'post_title' => 'Fourth',
-			'post_date' => '2012-04-01 12:00:00'
+			'post_date'  => '2012-04-01 12:00:00',
 		) );
 
+		// Use pages to test post-type adjacency
+		$page_one = $this->factory->post->create_and_get( array(
+			'post_title' => 'First Page',
+			'post_date'  => '2013-01-01 12:00:00',
+			'post_type'  => 'page',
+		) );
+
+		$page_two = $this->factory->post->create_and_get( array(
+			'post_title' => 'Second Page',
+			'post_date'  => '2013-02-01 12:00:00',
+			'post_type'  => 'page',
+		) );
+
 		// Add some meta so we can join the postmeta table and query
 		add_post_meta( $post_three->ID, 'unit_test_meta', 'waffle' );
 
@@ -233,6 +246,13 @@
 		$this->go_to( get_permalink( $post_one->ID ) );
 		$this->assertEquals( $post_three, get_adjacent_post( false, null, false ) );
 		remove_filter( 'get_next_post_sort', array( $this, 'filter_next_post_sort_limit' ) );
+
+		// Test post-type specificity
+		$this->go_to( get_permalink( $page_one ) );
+		$this->assertEquals( $page_two, get_adjacent_post( false, null, false ) );
+
+		$this->go_to( get_permalink( $page_two ) );
+		$this->assertEquals( $page_one, get_adjacent_post( false, null, true ) );
 	}
 
 	/**