--- a/widget/os2/nsFilePicker.cpp
+++ b/widget/os2/nsFilePicker.cpp
@@ -113,17 +113,19 @@ NS_IMETHODIMP nsFilePicker::Show(PRInt16
 
   FILEDLG filedlg;
   memset(&filedlg, 0, sizeof(FILEDLG));
   filedlg.cbSize = sizeof(FILEDLG);
   filedlg.pszTitle = title;
 
   if (mMode == modeGetFolder) {
     PL_strncat(filedlg.szFullFile, initialDir.get(), MAX_PATH);
-    PL_strncat(filedlg.szFullFile, "\\", 1);
+    if (filedlg.szFullFile[0] && 
+        filedlg.szFullFile[strlen(filedlg.szFullFile) - 1] != '\\') 
+      PL_strncat(filedlg.szFullFile, "\\", 1);
     PL_strncat(filedlg.szFullFile, "^", 1);
     filedlg.fl = FDS_OPEN_DIALOG | FDS_CENTER;
     filedlg.pfnDlgProc = DirDialogProc;
     DosError(FERR_DISABLEHARDERR);
     WinFileDlg(HWND_DESKTOP, mWnd, &filedlg);
     DosError(FERR_ENABLEHARDERR);
     char* tempptr = strchr(filedlg.szFullFile, '^');
     if (tempptr)
@@ -134,17 +136,19 @@ NS_IMETHODIMP nsFilePicker::Show(PRInt16
         mDisplayDirectory = do_CreateInstance("@mozilla.org/file/local;1");
       if (mDisplayDirectory)
         mDisplayDirectory->InitWithNativePath(nsDependentCString(filedlg.szFullFile));
       mFile.Assign(filedlg.szFullFile);
     }
   }
   else {
     PL_strncpy(filedlg.szFullFile, initialDir.get(), MAX_PATH);
-    PL_strncat(filedlg.szFullFile, "\\", 1);
+    if (filedlg.szFullFile[0] && 
+        filedlg.szFullFile[strlen(filedlg.szFullFile) - 1] != '\\') 
+      PL_strncat(filedlg.szFullFile, "\\", 1);
     PL_strncat(filedlg.szFullFile, fileBuffer.get(), MAX_PATH);
     filedlg.fl = FDS_CENTER;
     if (mMode == modeSave) {
        filedlg.fl |= FDS_SAVEAS_DIALOG | FDS_ENABLEFILELB;
     } else if (mMode == modeOpenMultiple) {
        filedlg.fl |= FDS_MULTIPLESEL | FDS_OPEN_DIALOG;
     } else {
        filedlg.fl |= FDS_OPEN_DIALOG;