diff --git a/Storage/Disk/Encodings/MFM/SegmentParser.cpp b/Storage/Disk/Encodings/MFM/SegmentParser.cpp
index 5943fbb0b..8fd0c3810 100644
--- a/Storage/Disk/Encodings/MFM/SegmentParser.cpp
+++ b/Storage/Disk/Encodings/MFM/SegmentParser.cpp
@@ -56,7 +56,7 @@ std::map<std::size_t, Storage::Encodings::MFM::Sector> Storage::Encodings::MFM::
 						case 2:	new_sector->address.sector = shifter.get_byte(); ++position; break;
 						case 3:
 							new_sector->size = shifter.get_byte();
-							size = static_cast<std::size_t>(128 << new_sector->size);
+							size = static_cast<std::size_t>(128 << (new_sector->size&7));
 							++position;
 							is_reading = false;
 							shifter.set_should_obey_syncs(true);