diff --git a/cores/esp32/esp32-hal.h b/cores/esp32/esp32-hal.h
index 331ee42cbfd7d9f61434144b95a9563c57ed9fa7..69d316f742b804a8d5e07abe5f066f596ea70ca4 100644
--- a/cores/esp32/esp32-hal.h
+++ b/cores/esp32/esp32-hal.h
@@ -33,6 +33,11 @@ extern "C" {
 #include <string.h>
 #include <math.h>
 
+//forward declaration from freertos/portmacro.h
+void vPortYield( void );
+#define yield() vPortYield()
+#define optimistic_yield(u)
+
 #define ESP_REG(addr) *((volatile uint32_t *)(addr))
 #define NOP() asm volatile ("nop")