diff --git a/Makefile b/Makefile
index aa8cd93..0f144e0 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@ check_targets=$(addprefix check_,${all_bins})
 src_dirs=$(sort $(dir $(wildcard ${src_dir}/**/)))
 includes=$(patsubst %,-I%,${src_dirs})
 
-CFLAGS+=${includes} -march=native -fPIC
+CFLAGS+=${includes} -march=native -fPIC -DSMALL_OPTI
 LDFLAGS+=
 ifdef USE_PTHREAD
 LDFLAGS+=-lpthread
diff --git a/src/thread/thread.c b/src/thread/thread.c
index af1dffc..3b73933 100644
--- a/src/thread/thread.c
+++ b/src/thread/thread.c
@@ -73,6 +73,11 @@ int thread_yield(void)
     if (TAILQ_EMPTY(&scheduler_fifo))
         return 0;
 
+#ifdef SMALL_OPTI
+    if (!IS_FINISHED(running) && !IS_WAITING(running) && !IS_MUTEX_WAITING(running))
+        return 0;
+#endif
+
     if (HAS_STATUS(running, MUTEX_LOCKING)) {
         if (running->mutex_prio > 0) {
             running->mutex_prio--;