--- a/js/xpconnect/src/XPCConvert.cpp
+++ b/js/xpconnect/src/XPCConvert.cpp
@@ -1703,24 +1703,16 @@ XPCConvert::JSStringWithSize2Native(void
         case nsXPTType::T_PSTRING_SIZE_IS:
         {
             if (s.isUndefined() || s.isNull()) {
                 if (0 != count) {
                     if (pErr)
                         *pErr = NS_ERROR_XPC_NOT_ENOUGH_CHARS_IN_STRING;
                     return false;
                 }
-                if (0 != count) {
-                    len = (count + 1) * sizeof(char);
-                    if (!(*((void**)d) = moz_xmalloc(len)))
-                        return false;
-                    return true;
-                }
-                // else ...
-
                 *((char**)d) = nullptr;
                 return true;
             }
 
             JSString* str = ToString(cx, s);
             if (!str) {
                 return false;
             }