diff --git a/src/wp-includes/taxonomy.php b/src/wp-includes/taxonomy.php
index 9865f42be7..78dd52ced9 100644
--- a/src/wp-includes/taxonomy.php
+++ b/src/wp-includes/taxonomy.php
@@ -2579,8 +2579,13 @@ function wp_insert_term( $term, $taxonomy, $args = array() ) {
 	if ( $args['parent'] > 0 && ! term_exists( (int) $args['parent'] ) ) {
 		return new WP_Error( 'missing_parent', __( 'Parent term does not exist.' ) );
 	}
+
 	$args['name'] = $term;
 	$args['taxonomy'] = $taxonomy;
+
+	// Coerce null description to strings, to avoid database errors.
+	$args['description'] = (string) $args['description'];
+
 	$args = sanitize_term($args, $taxonomy, 'db');
 
 	// expected_slashed ($name)
diff --git a/tests/phpunit/tests/term/wpInsertTerm.php b/tests/phpunit/tests/term/wpInsertTerm.php
index c3dea31247..386b66fa15 100644
--- a/tests/phpunit/tests/term/wpInsertTerm.php
+++ b/tests/phpunit/tests/term/wpInsertTerm.php
@@ -642,6 +642,23 @@ class Tests_Term_WpInsertTerm extends WP_UnitTestCase {
 
 	}
 
+	/**
+	 * @ticket 35321
+	 */
+	public function test_wp_insert_term_with_null_description() {
+
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$term = wp_insert_term( 'foo', 'wptests_tax', array(
+			'description' => null
+		) );
+
+		$term_object = get_term( $term['term_id'] );
+
+		$this->assertInstanceOf( 'WP_Term', $term_object );
+		$this->assertSame( '', $term_object->description );
+	}
+
 	/** Helpers **********************************************************/
 
 	public function deleted_term_cb( $term, $tt_id, $taxonomy, $deleted_term, $object_ids ) {