--- a/toolkit/mozapps/update/nsUpdateService.js
+++ b/toolkit/mozapps/update/nsUpdateService.js
@@ -958,17 +958,17 @@ function shouldUseService() {
     Cu.reportError("Unable to open kernel32! " + e);
     return false;
   }
 
   if (kernel32) {
     try {
       try {
         let GetVersionEx = kernel32.declare("GetVersionExW",
-                                            ctypes.default_abi,
+                                            ctypes.winapi_abi,
                                             BOOL,
                                             OSVERSIONINFOEXW.ptr);
         let winVer = OSVERSIONINFOEXW();
         winVer.dwOSVersionInfoSize = OSVERSIONINFOEXW.size;
 
         if (0 !== GetVersionEx(winVer.address())) {
           return winVer.wServicePackMajor >= 3;
         }