--- a/js/src/jsapi-tests/moz.build
+++ b/js/src/jsapi-tests/moz.build
@@ -139,17 +139,17 @@ if CONFIG['ENABLE_STREAMS']:
 
 
 if CONFIG['NIGHTLY_BUILD']:
     # The Error interceptor only exists on Nightly.
     UNIFIED_SOURCES += [
         'testErrorInterceptor.cpp',
     ]
 
-if CONFIG['JS_BUILD_BINAST'] and CONFIG['JS_STANDALONE'] and CONFIG['OS_TARGET'] != 'WINNT':
+if CONFIG['JS_BUILD_BINAST'] and CONFIG['JS_STANDALONE']:
     # Standalone builds leave the source directory untouched,
     # which lets us run tests with the data files intact.
     # Otherwise, in the current state of the build system,
     # we can't have data files in js/src tests.
     UNIFIED_SOURCES += [
         'testBinASTReader.cpp',
         'testBinTokenReaderTester.cpp'
     ]

--- a/js/src/jsapi-tests/testBinASTReader.cpp
+++ b/js/src/jsapi-tests/testBinASTReader.cpp
@@ -76,21 +76,27 @@ runTestFromPath(JSContext* cx, const cha
     while (auto entry = readdir(dir)) {
         const char* d_name = entry->d_name;
         const bool isDirectory = entry->d_type == DT_DIR;
 
 
 #elif defined(XP_WIN)
     MOZ_ASSERT(path[pathlen - 1] == '\\');
 
-    const char PATTERN[] = "*";
+    Vector<char> pattern(cx);
+    if (!pattern.append(path, pathlen))
+        MOZ_CRASH();
+    if (!pattern.append('*'))
+        MOZ_CRASH();
+    if (!pattern.append('\0'))
+        MOZ_CRASH();
 
     WIN32_FIND_DATA FindFileData;
     enterJsDirectory();
-    HANDLE hFind = FindFirstFile(PATTERN, &FindFileData);
+    HANDLE hFind = FindFirstFile(pattern.begin(), &FindFileData);
     exitJsDirectory();
     for (bool found = (hFind != INVALID_HANDLE_VALUE);
             found;
             found = FindNextFile(hFind, &FindFileData))
     {
         const char* d_name = FindFileData.cFileName;
         const bool isDirectory = FindFileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY;