diff --git a/Zframework/theme.lua b/Zframework/theme.lua
index b5de3aa1..0e2e9fb3 100644
--- a/Zframework/theme.lua
+++ b/Zframework/theme.lua
@@ -33,9 +33,9 @@ function THEME.calculate(Y,M,D)
 
 		--Z day (Feb./Mar./Apr./May./June. 26)
 		D=="26"and(
-			M=="01"or M=="02"and'zday1'or
-			M=="03"or M=="04"and'zday2'or
-			M=="05"or M=="06"and'zday3'
+			(M=="01"or M=="02")and'zday1'or
+			(M=="03"or M=="04")and'zday2'or
+			(M=="05"or M=="06")and'zday3'
 		)or
 
 		'classic'