diff --git a/src/wp-includes/post-functions.php b/src/wp-includes/post-functions.php
index 1d6ae6fc39..05663968de 100644
--- a/src/wp-includes/post-functions.php
+++ b/src/wp-includes/post-functions.php
@@ -3042,7 +3042,7 @@ function wp_insert_post( $postarr, $wp_error = false ) {
 
 	// These variables are needed by compact() later.
 	$post_content_filtered = $postarr['post_content_filtered'];
-	$post_author = empty( $postarr['post_author'] ) ? $user_id : $postarr['post_author'];
+	$post_author = isset( $postarr['post_author'] ) ? $postarr['post_author'] : $user_id;
 	$ping_status = empty( $postarr['ping_status'] ) ? get_default_comment_status( $post_type, 'pingback' ) : $postarr['ping_status'];
 	$to_ping = isset( $postarr['to_ping'] ) ? sanitize_trackback_urls( $postarr['to_ping'] ) : '';
 	$pinged = isset( $postarr['pinged'] ) ? $postarr['pinged'] : '';
diff --git a/tests/phpunit/tests/post.php b/tests/phpunit/tests/post.php
index d6ce0309e6..b3d7b0a73a 100644
--- a/tests/phpunit/tests/post.php
+++ b/tests/phpunit/tests/post.php
@@ -1200,4 +1200,22 @@ class Tests_Post extends WP_UnitTestCase {
 		// Teardown
 		wp_set_current_user( $old_uid );
 	}
+
+	/**
+	 * @ticket 32585
+	 */
+	public function test_wp_insert_post_author_zero() {
+		$post_id = $this->factory->post->create( array( 'post_author' => 0 ) );
+
+		$this->assertEquals( 0, get_post( $post_id )->post_author );
+	}
+
+	/**
+	 * @ticket 32585
+	 */
+	public function test_wp_insert_post_author_null() {
+		$post_id = $this->factory->post->create( array( 'post_author' => null ) );
+
+		$this->assertEquals( $this->author_id, get_post( $post_id )->post_author );
+	}
 }