Index: trunk/src/org/openstreetmap/josm/io/session/SessionReader.java
===================================================================
--- trunk/src/org/openstreetmap/josm/io/session/SessionReader.java	(revision 9645)
+++ trunk/src/org/openstreetmap/josm/io/session/SessionReader.java	(revision 9646)
@@ -43,4 +43,5 @@
 import org.openstreetmap.josm.gui.progress.NullProgressMonitor;
 import org.openstreetmap.josm.gui.progress.ProgressMonitor;
+import org.openstreetmap.josm.io.Compression;
 import org.openstreetmap.josm.io.IllegalDataException;
 import org.openstreetmap.josm.tools.MultiMap;
@@ -202,5 +203,5 @@
             if (file != null) {
                 try {
-                    return new BufferedInputStream(new FileInputStream(file));
+                    return new BufferedInputStream(Compression.getUncompressedFileInputStream(file));
                 } catch (FileNotFoundException e) {
                     throw new IOException(tr("File ''{0}'' does not exist.", file.getPath()), e);