diff --git a/mozilla/widget/src/windows/nsFilePicker.cpp b/mozilla/widget/src/windows/nsFilePicker.cpp
index 2235eaf1128..6c18b5be7e8 100644
--- a/mozilla/widget/src/windows/nsFilePicker.cpp
+++ b/mozilla/widget/src/windows/nsFilePicker.cpp
@@ -155,6 +155,8 @@ NS_IMETHODIMP nsFilePicker::Show(PRInt16 *retval)
     ofn.Flags = OFN_SHAREAWARE | OFN_LONGNAMES | OFN_OVERWRITEPROMPT | OFN_HIDEREADONLY;
 
     if (mMode == modeOpen) {
+      // FILE MUST EXIST!
+      ofn.Flags |= OFN_FILEMUSTEXIST;
       result = ::GetOpenFileName(&ofn);
     }
     else if (mMode == modeSave) {
diff --git a/mozilla/widget/src/windows/nsFileWidget.cpp b/mozilla/widget/src/windows/nsFileWidget.cpp
index da0c55e4daf..39e1dade5a6 100644
--- a/mozilla/widget/src/windows/nsFileWidget.cpp
+++ b/mozilla/widget/src/windows/nsFileWidget.cpp
@@ -141,6 +141,8 @@ PRBool nsFileWidget::Show()
 
 
   if (mMode == eMode_load) {
+    // FILE MUST EXIST!
+    ofn.Flags |= OFN_FILEMUSTEXIST;
     result = ::GetOpenFileName(&ofn);
   }
   else if (mMode == eMode_save) {