diff --git a/tests/phpunit/tests/cache.php b/tests/phpunit/tests/cache.php
index fd93a0940b..d3805383a7 100644
--- a/tests/phpunit/tests/cache.php
+++ b/tests/phpunit/tests/cache.php
@@ -281,7 +281,13 @@ class Tests_Cache extends WP_UnitTestCase {
 		wp_cache_init();
 
 		global $wp_object_cache;
-		$this->assertEquals( $wp_object_cache, $new_blank_cache_object );
+
+		if ( wp_using_ext_object_cache() ) {
+			// External caches will contain property values that contain non-matching resource IDs
+			$this->assertInstanceOf( 'WP_Object_Cache', $wp_object_cache  );
+		} else {
+			$this->assertEquals( $wp_object_cache, $new_blank_cache_object );
+		}
 	}
 
 	function test_wp_cache_replace() {