diff --git a/src/mzscheme/src/port.c b/src/mzscheme/src/port.c
index 5272e32c7b..76909f678c 100644
--- a/src/mzscheme/src/port.c
+++ b/src/mzscheme/src/port.c
@@ -8595,8 +8595,6 @@ void scheme_kickoff_green_thread_time_slice_timer(long usec) {
   scheme_start_itimer_thread(usec);
 #elif defined(USE_PTHREAD_THREAD_TIMER)
   scheme_start_itimer_thread(usec);
-#else
-  #error scheme_start_green_thread_time_slice_timer NOT IMPLEMENTED
 #endif
 }