diff --git a/cache/classes/helper.php b/cache/classes/helper.php
index 96bedb2bb59..015ed8a184b 100644
--- a/cache/classes/helper.php
+++ b/cache/classes/helper.php
@@ -718,7 +718,8 @@ class cache_helper {
             return $stores;
         } else {
             $stores = self::get_cache_stores($definition);
-            if (count($stores) === 0) {
+            // If mappingsonly is set, having 0 stores is ok.
+            if ((count($stores) === 0) && (!$definition->is_for_mappings_only())) {
                 // No suitable stores we found for the definition. We need to come up with a sensible default.
                 // If this has happened we can be sure that the user has mapped custom stores to either the
                 // mode of the definition. The first alternative to try is the system default for the mode.
diff --git a/cache/tests/cache_test.php b/cache/tests/cache_test.php
index 2267afad415..5a85f1465e8 100644
--- a/cache/tests/cache_test.php
+++ b/cache/tests/cache_test.php
@@ -470,6 +470,33 @@ class core_cache_testcase extends advanced_testcase {
         $this->assertEquals('Test has no value really.', $cache->get('Test'));
     }
 
+    /**
+     * Test the mappingsonly setting.
+     */
+    public function test_definition_mappings_only() {
+        $instance = cache_config_phpunittest::instance(true);
+        $instance->phpunit_add_definition('phpunit/mappingsonly', array(
+            'mode' => cache_store::MODE_APPLICATION,
+            'component' => 'phpunit',
+            'area' => 'mappingsonly',
+            'mappingsonly' => true
+        ));
+        $instance->phpunit_add_definition('phpunit/nonmappingsonly', array(
+            'mode' => cache_store::MODE_APPLICATION,
+            'component' => 'phpunit',
+            'area' => 'nonmappingsonly',
+            'mappingsonly' => false
+        ));
+
+        $cacheonly = cache::make('phpunit', 'mappingsonly');
+        $this->assertInstanceOf('cache_application', $cacheonly);
+        $this->assertEquals('cachestore_dummy', $cacheonly->phpunit_get_store_class());
+
+        $cachenon = cache::make('phpunit', 'nonmappingsonly');
+        $this->assertInstanceOf('cache_application', $cachenon);
+        $this->assertEquals('cachestore_file', $cachenon->phpunit_get_store_class());
+    }
+
     /**
      * Test a very basic definition.
      */