Index: trunk/src/org/openstreetmap/josm/tools/Logging.java
===================================================================
--- trunk/src/org/openstreetmap/josm/tools/Logging.java	(revision 14060)
+++ trunk/src/org/openstreetmap/josm/tools/Logging.java	(revision 14062)
@@ -85,5 +85,5 @@
          * Set output stream to one acquired from calling outputStreamSupplier
          */
-        public void reacquireOutputStream() {
+        public synchronized void reacquireOutputStream() {
             final OutputStream reacquiredStream = this.outputStreamSupplier.get();