diff --git a/thermion_dart/native/include/c_api/APIBoundaryTypes.h b/thermion_dart/native/include/c_api/APIBoundaryTypes.h
index 6ada7065..43e4174e 100644
--- a/thermion_dart/native/include/c_api/APIBoundaryTypes.h
+++ b/thermion_dart/native/include/c_api/APIBoundaryTypes.h
@@ -9,6 +9,8 @@ extern "C"
 #include <stdint.h>
 
 #include "APIExport.h"
+
+	typedef void (*VoidCallback)(int32_t requestId);
 	
 	typedef int32_t EntityId;
 	typedef struct TCamera TCamera;