--- a/toolkit/components/osfile/ospath_unix_back.jsm
+++ b/toolkit/components/osfile/ospath_unix_back.jsm
@@ -96,23 +96,28 @@ if (typeof Components != "undefined") {
          case "..":
            if (stack.length == 0) {
              if (absolute) {
                throw new Error("Path is ill-formed: attempting to go past root");
              } else {
                stack.push("..");
              }
            } else {
-             stack.pop();
+             if (stack[stack.length - 1] == "..") {
+               stack.push("..");
+             } else {
+               stack.pop();
+             }
            }
            break;
          default:
            stack.push(v);
          }
        });
+       exports.OS.Shared.LOG("normalize", "stack", stack.toSource());
        let string = stack.join("/");
        return absolute ? "/" + string : string;
      },
      /**
       * Return the components of a path.
       * You should generally apply this function to a normalized path.
       *
       * @return {{

--- a/toolkit/components/osfile/ospath_win_back.jsm
+++ b/toolkit/components/osfile/ospath_win_back.jsm
@@ -192,17 +192,21 @@ if (typeof Components != "undefined") {
          case "..":
            if (stack.length == 0) {
              if (absolute) {
                throw new Error("Path is ill-formed: attempting to go past root");
              } else {
               stack.push("..");
              }
            } else {
-             stack.pop();
+             if (stack[stack.length - 1] == "..") {
+               stack.push("..");
+             } else {
+               stack.pop();
+             }
            }
            break;
          default:
            stack.push(v);
          }
        });
 
        // Put everything back together