diff --git a/src/wp-includes/theme.php b/src/wp-includes/theme.php
index 5fa7a23146..b707990dcf 100644
--- a/src/wp-includes/theme.php
+++ b/src/wp-includes/theme.php
@@ -2517,6 +2517,9 @@ function add_theme_support( $feature, ...$args ) {
 				unset( $post_formats['standard'] );
 
 				$args[0] = array_intersect( $args[0], array_keys( $post_formats ) );
+			} else {
+				_doing_it_wrong( "add_theme_support( 'post-formats' )", __( 'You need to pass an array of types.' ), '5.6.0' );
+				return false;
 			}
 			break;
 
diff --git a/tests/phpunit/tests/post/formats.php b/tests/phpunit/tests/post/formats.php
index 44cedfc9a6..e9b0424ffb 100644
--- a/tests/phpunit/tests/post/formats.php
+++ b/tests/phpunit/tests/post/formats.php
@@ -8,6 +8,13 @@ class Tests_Post_Formats extends WP_UnitTestCase {
 		parent::setUp();
 	}
 
+	function test_post_format_doing_it_wrong() {
+		$this->setExpectedIncorrectUsage( "add_theme_support( 'post-formats' )" );
+
+		// The second parameter should be an array
+		$this->assertFalse( add_theme_support( 'post-formats' ) );
+	}
+
 	function test_set_get_post_format_for_post() {
 		$post_id = self::factory()->post->create();