diff --git a/classes/local/store/object_file_system.php b/classes/local/store/object_file_system.php
index de30f1d2..38e12a2c 100644
--- a/classes/local/store/object_file_system.php
+++ b/classes/local/store/object_file_system.php
@@ -249,7 +249,7 @@ public function is_file_readable_externally_by_hash($contenthash) {
         if ($contenthash === sha1('')) {
             // Files with empty size are either directories or empty.
             // We handle these virtually.
-            return true;
+            return false;
         }
 
         $path = $this->get_external_path_from_hash($contenthash, false);
diff --git a/tests/object_file_system_test.php b/tests/object_file_system_test.php
index 3621c064..0119f23e 100644
--- a/tests/object_file_system_test.php
+++ b/tests/object_file_system_test.php
@@ -76,8 +76,21 @@ public function test_get_remote_path_from_storedfile_returns_external_path_if_no
     public function test_get_remote_path_from_storedfile_returns_external_path_if_duplicated_and_preferexternal() {
         set_config('preferexternal', true, 'tool_objectfs');
         $this->reset_file_system(); // Needed to load new config.
-        $file = $this->create_duplicated_file();
-        $expectedpath = $this->get_external_path_from_storedfile($file);
+        $file = $this->create_local_file();
+        $expectedpath = $this->get_local_path_from_storedfile($file);
+
+        $reflection = new \ReflectionMethod(object_file_system::class, 'get_remote_path_from_storedfile');
+        $reflection->setAccessible(true);
+        $actualpath = $reflection->invokeArgs($this->filesystem, [$file]);
+
+        $this->assertEquals($expectedpath, $actualpath);
+    }
+
+    public function test_get_remote_path_from_empty_storedfile_returns_internal_path_if_duplicated_and_preferexternal() {
+        set_config('preferexternal', true, 'tool_objectfs');
+        $this->reset_file_system(); // Needed to load new config.
+        $file = $this->create_duplicated_file('');
+        $expectedpath = $this->get_local_path_from_storedfile($file);
 
         $reflection = new \ReflectionMethod(object_file_system::class, 'get_remote_path_from_storedfile');
         $reflection->setAccessible(true);