diff --git a/Main/src/HFE.cpp b/Main/src/HFE.cpp
index 526d3a7..c53e618 100644
--- a/Main/src/HFE.cpp
+++ b/Main/src/HFE.cpp
@@ -195,9 +195,11 @@ formatError: ::SetLastError(ERROR_BAD_FORMAT);
 		// - construction of InternalTracks for both Heads
 		if (!cylInfos[cyl].IsValid()) // maybe an error during Image creation?
 			return CTrackReaderWriter::Invalid;
-		internalTracks[cyl][0]=BytesToTrack( ReadTrackBytes(cyl,0) );
-		if (!params.flippyDisk) // flippy disks not known to be represented backwards in *.HFE, hence always fail if this flag is set
-			internalTracks[cyl][1]=BytesToTrack( ReadTrackBytes(cyl,1) );
+		if (!internalTracks[cyl][0])
+			internalTracks[cyl][0]=BytesToTrack( ReadTrackBytes(cyl,0) );
+		if (!internalTracks[cyl][1])
+			if (!params.flippyDisk) // flippy disks not known to be represented backwards in *.HFE, hence always fail if this flag is set
+				internalTracks[cyl][1]=BytesToTrack( ReadTrackBytes(cyl,1) );
 		const PInternalTrack &rit=internalTracks[cyl][head];
 		return	rit ? *rit : CTrackReaderWriter::Invalid;
 	}