diff --git a/iso_week.h b/iso_week.h
index 45c326d..0f010e5 100644
--- a/iso_week.h
+++ b/iso_week.h
@@ -818,8 +818,8 @@ inline
 weeks
 operator-(const weeknum& x, const weeknum& y) NOEXCEPT
 {
-    return weeks{static_cast<weeks::rep>(static_cast<unsigned>(x)
-                                       - static_cast<unsigned>(y))};
+    return weeks{static_cast<weeks::rep>(static_cast<unsigned>(x)) -
+                 static_cast<weeks::rep>(static_cast<unsigned>(y))};
 }
 
 CONSTCD11