diff --git a/app/models/concerns/mentionable.rb b/app/models/concerns/mentionable.rb
index 5ac56ac6fa01a7125b2573ad26659c8ae773f603..6eddeab515e429f45d1122519fe7d0ffa4294152 100644
--- a/app/models/concerns/mentionable.rb
+++ b/app/models/concerns/mentionable.rb
@@ -92,7 +92,7 @@ module Mentionable
   # Uses regex to quickly determine if mentionables might be referenced
   # Allows heavy processing to be skipped
   def matches_cross_reference_regex?
-    reference_pattern = if project.default_issues_tracker?
+    reference_pattern = if !project || project.default_issues_tracker?
                           ReferenceRegexes::DEFAULT_PATTERN
                         else
                           ReferenceRegexes::EXTERNAL_PATTERN