diff --git a/src/mzscheme/sconfig.h b/src/mzscheme/sconfig.h
index bbd8fe1bf6..371c8f1900 100644
--- a/src/mzscheme/sconfig.h
+++ b/src/mzscheme/sconfig.h
@@ -575,6 +575,8 @@
 
 # include "uconfig.h"
 
+# undef USE_ITIMER
+
 # undef HAS_STANDARD_IOB
 # define HAS_CYGWIN_IOB
 # define MZ_BINARY O_BINARY