diff --git a/src/common/tusb_fifo.h b/src/common/tusb_fifo.h
index 6e0ecdc8..0276c804 100644
--- a/src/common/tusb_fifo.h
+++ b/src/common/tusb_fifo.h
@@ -53,6 +53,7 @@ extern "C" {
 #endif
 
 #if CFG_FIFO_MUTEX
+#include "osal/osal.h"
 #define tu_fifo_mutex_t  osal_mutex_t
 #endif