diff --git a/definitions/patterns_re.txt b/definitions/patterns_re.txt
index 54f2462..0f86264 100644
--- a/definitions/patterns_re.txt
+++ b/definitions/patterns_re.txt
@@ -75,3 +75,6 @@ chr\s*\(\s*['"]?\s*((95)|(0[Xx]5[Ff]))\s*['"]?\s*\)
 
 #Malware inffected files sometimes marked with comments like /*87cda*/ to avoid infect again
 \/\*[a-z0-9]{5}\*\/
+
+# XOR-ed strings with custom math
+%\(\d+\-\d+\+\d+\)==\(\-\d+\+\d+\+\d+\)
\ No newline at end of file