diff --git a/src/basicio.cpp b/src/basicio.cpp
index 6977d9e9..315e1bdd 100644
--- a/src/basicio.cpp
+++ b/src/basicio.cpp
@@ -280,6 +280,7 @@ namespace Exiv2 {
             p_->hFile_ = 0;
 #else
             if (p_->isWriteable_) {
+                seek(0, BasicIo::beg);
                 write(p_->pMappedArea_, p_->mappedLength_);
             }
             if (p_->isMalloced_) {