diff --git a/Storage/Disk/DiskImage/Formats/WOZ.cpp b/Storage/Disk/DiskImage/Formats/WOZ.cpp
index bea9fd702..9dd11b047 100644
--- a/Storage/Disk/DiskImage/Formats/WOZ.cpp
+++ b/Storage/Disk/DiskImage/Formats/WOZ.cpp
@@ -112,10 +112,22 @@ int WOZ::get_head_count() {
 }
 
 long WOZ::file_offset(Track::Address address) {
-	// Calculate table position; if this track is defined to be unformatted, return no track.
-	const int table_position = address.head * (is_3_5_disk_ ? 80 : 160) +
-		(is_3_5_disk_ ? address.position.as_int() : address.position.as_quarter());
-	if(track_map_[table_position] == 0xff) return NoSuchTrack;
+	// Calculate table position.
+	int table_position;
+	if(!is_3_5_disk_) {
+		table_position = address.head * 160 + address.position.as_quarter();
+	} else {
+		if(type_ == Type::WOZ1) {
+			table_position = address.head * 80 + address.position.as_int();
+		} else {
+			table_position = address.head + (address.position.as_int() * 2);
+		}
+	}
+
+	// Check that this track actually exists.
+	if(track_map_[table_position] == 0xff) {
+		return NoSuchTrack;
+	}
 
 	// Seek to the real track.
 	switch(type_) {
@@ -125,9 +137,17 @@ long WOZ::file_offset(Track::Address address) {
 	}
 }
 
+bool WOZ::tracks_differ(Track::Address lhs, Track::Address rhs) {
+	const long offset1 = file_offset(lhs);
+	const long offset2 = file_offset(rhs);
+	return offset1 != offset2;
+}
+
 std::shared_ptr<Track> WOZ::get_track_at_position(Track::Address address) {
 	const long offset = file_offset(address);
-	if(offset == NoSuchTrack) return nullptr;
+	if(offset == NoSuchTrack) {
+		return nullptr;
+	}
 
 	// Seek to the real track.
 	std::vector<uint8_t> track_contents;
diff --git a/Storage/Disk/DiskImage/Formats/WOZ.hpp b/Storage/Disk/DiskImage/Formats/WOZ.hpp
index f131f46c7..cf2d2e5a6 100644
--- a/Storage/Disk/DiskImage/Formats/WOZ.hpp
+++ b/Storage/Disk/DiskImage/Formats/WOZ.hpp
@@ -31,6 +31,7 @@ class WOZ: public DiskImage {
 		std::shared_ptr<Track> get_track_at_position(Track::Address address) final;
 		void set_tracks(const std::map<Track::Address, std::shared_ptr<Track>> &tracks) final;
 		bool get_is_read_only() final;
+		bool tracks_differ(Track::Address, Track::Address) final;
 
 	private:
 		Storage::FileHolder file_;