diff --git a/knowledge base/ruby.md b/knowledge base/ruby.md
index 1e5b568..defc332 100644
--- a/knowledge base/ruby.md	
+++ b/knowledge base/ruby.md	
@@ -29,6 +29,10 @@ SSL_CERT_FILE='path/to/ssl.cert'
   <summary>Usage</summary>
 
 ```sh
+# Check file syntax.
+# Does *not* run the code.
+ruby -c '/etc/gitlab/gitlab.rb'
+
 # Create ruby gems from code.
 gem build