diff --git a/Storage/MassStorage/Formats/HFV.cpp b/Storage/MassStorage/Formats/HFV.cpp
index 85fa20847..5b617ad1e 100644
--- a/Storage/MassStorage/Formats/HFV.cpp
+++ b/Storage/MassStorage/Formats/HFV.cpp
@@ -31,3 +31,9 @@ std::vector<uint8_t> HFV::get_block(size_t address) {
 	file_.seek(file_offset, SEEK_SET);
 	return file_.read(get_block_size());
 }
+
+void HFV::set_block(size_t address, const std::vector<uint8_t> &contents) {
+	const long file_offset = long(get_block_size() * address);
+	file_.seek(file_offset, SEEK_SET);
+	file_.write(contents);
+}
diff --git a/Storage/MassStorage/Formats/HFV.hpp b/Storage/MassStorage/Formats/HFV.hpp
index c3c556ee6..a44a29bdc 100644
--- a/Storage/MassStorage/Formats/HFV.hpp
+++ b/Storage/MassStorage/Formats/HFV.hpp
@@ -29,6 +29,7 @@ class HFV: public MassStorageDevice {
 		size_t get_block_size() final;
 		size_t get_number_of_blocks() final;
 		std::vector<uint8_t> get_block(size_t address) final;
+		void set_block(size_t address, const std::vector<uint8_t> &) final;
 
 };