diff --git a/io/source/stm/omark.cxx b/io/source/stm/omark.cxx
index cbbfa0fff1c6..62b4c34c848b 100644
--- a/io/source/stm/omark.cxx
+++ b/io/source/stm/omark.cxx
@@ -939,7 +939,7 @@ void OMarkableInputStream::checkMarksAndFlush()
 
     // find the smallest mark
     sal_Int32 nNextFound = m_nCurrentPos;
-    for( ii = m_mapMarks.begin() ; ii != m_mapMarks.end() ; ii ) {
+    for( ii = m_mapMarks.begin() ; ii != m_mapMarks.end() ; ++ii ) {
         if( (*ii).second <= nNextFound )  {
             nNextFound = (*ii).second;
         }