diff --git a/src/ameba/reportable.cr b/src/ameba/reportable.cr
index 35453950..e31ef3a7 100644
--- a/src/ameba/reportable.cr
+++ b/src/ameba/reportable.cr
@@ -5,7 +5,7 @@ module Ameba
     getter issues = [] of Issue
 
     # Adds a new issue to the list of issues.
-    def add_issue(rule, location, end_location, message, status = nil)
+    def add_issue(rule, location : Crystal::Location?, end_location : Crystal::Location?, message, status = nil)
       status ||= :disabled if location_disabled?(location, rule)
       issues << Issue.new rule, location, end_location, message, status
     end