diff --git a/src/common/wfstream.cpp b/src/common/wfstream.cpp
index 3605e2a707..c7c06b57ba 100644
--- a/src/common/wfstream.cpp
+++ b/src/common/wfstream.cpp
@@ -87,7 +87,7 @@ size_t wxFileInputStream::OnSysRead(void *buffer, size_t size)
 
 off_t wxFileInputStream::OnSysSeek(off_t pos, wxSeekMode mode)
 {
-    return m_file->Seek(pos, mode);
+    return m_file->Seek(pos, mode) ;
 }
 
 off_t wxFileInputStream::OnSysTell() const
@@ -244,7 +244,7 @@ size_t wxFFileInputStream::OnSysRead(void *buffer, size_t size)
 
 off_t wxFFileInputStream::OnSysSeek(off_t pos, wxSeekMode mode)
 {
-    return m_file->Seek(pos, mode);
+    return ( m_file->Seek(pos, mode) ? pos : wxInvalidOffset );
 }
 
 off_t wxFFileInputStream::OnSysTell() const
@@ -317,7 +317,7 @@ off_t wxFFileOutputStream::OnSysTell() const
 
 off_t wxFFileOutputStream::OnSysSeek(off_t pos, wxSeekMode mode)
 {
-    return m_file->Seek(pos, mode);
+    return ( m_file->Seek(pos, mode) ? pos : wxInvalidOffset );
 }
 
 void wxFFileOutputStream::Sync()