diff --git a/backends/timer/sdl/sdl-timer.cpp b/backends/timer/sdl/sdl-timer.cpp
index a1e34c8d202..66031cd4ba9 100644
--- a/backends/timer/sdl/sdl-timer.cpp
+++ b/backends/timer/sdl/sdl-timer.cpp
@@ -29,7 +29,7 @@
 
 #include "common/textconsole.h"
 
-static bool timerInstalled = false;
+static volatile bool timerInstalled = false;
 
 static Uint32 timer_handler(Uint32 interval, void *param) {
 	if (!timerInstalled)