diff --git a/src/kits/network/libnetapi/NetworkCookie.cpp b/src/kits/network/libnetapi/NetworkCookie.cpp
index 615e218566..0dcef0e365 100644
--- a/src/kits/network/libnetapi/NetworkCookie.cpp
+++ b/src/kits/network/libnetapi/NetworkCookie.cpp
@@ -245,7 +245,7 @@ BNetworkCookie&
 BNetworkCookie::SetMaxAge(int32 maxAge)
 {
 	BDateTime expiration = BDateTime::CurrentDateTime(B_GMT_TIME);
-	expiration.Time().AddSeconds(maxAge);
+	expiration.SetTime_t(expiration.Time_t() + maxAge);
 	return SetExpirationDate(expiration);
 }