diff --git a/lib/cpu.h b/lib/cpu.h
index 3ee3596b..b30d1f84 100644
--- a/lib/cpu.h
+++ b/lib/cpu.h
@@ -18,6 +18,13 @@
 # include <metal/processor/@PROJECT_PROCESSOR@/cpu.h>
 #else
 # include <metal/processor/generic/cpu.h>
+# include <metal/sleep.h>
+#endif
+
+#if defined(HAVE_PROCESSOR_CPU_H)
+#define metal_yield() metal_cpu_yield()
+#else
+#define metal_yield() metal_sleep_usec(1000)
 #endif
 
 #endif /* __METAL_CPU__H__ */