diff --git a/firmware/application/file.hpp b/firmware/application/file.hpp
index 7504fb93..96b71991 100644
--- a/firmware/application/file.hpp
+++ b/firmware/application/file.hpp
@@ -154,7 +154,7 @@ public:
 			return type == Type::Error;
 		}
 
-		const T& value() {
+		const T& value() const {
 			return value_;
 		}