diff --git a/firmware/common/fifo.hpp b/firmware/common/fifo.hpp
index 83ee06de..66c9c811 100644
--- a/firmware/common/fifo.hpp
+++ b/firmware/common/fifo.hpp
@@ -201,8 +201,8 @@ private:
 	}
 
 	T _data[size()];
-	size_t _in;
-	size_t _out;
+	volatile size_t _in;
+	volatile size_t _out;
 };
 
 #endif/*__FIFO_H__*/