diff --git a/topics/tutorials/custom_language_support/prerequisites.md b/topics/tutorials/custom_language_support/prerequisites.md
index 7abfe917f..92a558200 100644
--- a/topics/tutorials/custom_language_support/prerequisites.md
+++ b/topics/tutorials/custom_language_support/prerequisites.md
@@ -24,7 +24,7 @@ Make sure that the _Plugin DevKit_ and _Gradle_ plugins are enabled.
 
 <include from="snippets.md" element-id="pluginDevKitAvailability"/>
 
-Install and enable [Grammar-Kit](https://plugins.jetbrains.com/plugin/6606-grammar-kit) and [PsiViewer](https://plugins.jetbrains.com/plugin/227-psiviewer) plugins.
+Install and enable [Grammar-Kit](https://plugins.jetbrains.com/plugin/6606-grammar-kit) and [PsiViewer](https://plugins.jetbrains.com/plugin/227-psiviewer) (optionally) plugins.
 
 ## Create a Project