diff --git a/ss/SSMain.cc b/ss/SSMain.cc
index b6796d2..542a15b 100644
--- a/ss/SSMain.cc
+++ b/ss/SSMain.cc
@@ -22,7 +22,7 @@
 
 /* switch to the next screensaver mode after this many milliseconds */
 #define SSMODE_TIMEOUT_MSEC (1000*45)
-#define SCREENSAVER_MAX_RUNTIME (30*60*1000)
+#define SCREENSAVER_MAX_RUNTIME (30u*60u*1000u)
 
 static SDL_Event event;