diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 1c3fb82e3fa1..3c39779198c5 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -391,14 +391,15 @@ class SourceBufferHolder final
         length_(dataLength),
         ownsChars_(ownership == GiveOwnership)
     {
-        // Ensure that null buffers properly return an unowned, empty,
-        // null-terminated string.
-        static const char16_t NullChar_ = 0;
-        if (!get()) {
-            data_ = &NullChar_;
-            length_ = 0;
-            ownsChars_ = false;
-        }
+        fixEmptyBuffer();
+    }
+
+    SourceBufferHolder(UniqueTwoByteChars&& data, size_t dataLength)
+      : data_(data.release()),
+        length_(dataLength),
+        ownsChars_(true)
+    {
+        fixEmptyBuffer();
     }
 
     SourceBufferHolder(SourceBufferHolder&& other)
@@ -448,6 +449,17 @@ class SourceBufferHolder final
     SourceBufferHolder(SourceBufferHolder&) = delete;
     SourceBufferHolder& operator=(SourceBufferHolder&) = delete;
 
+    void fixEmptyBuffer() {
+        // Ensure that null buffers properly return an unowned, empty,
+        // null-terminated string.
+        static const char16_t NullChar_ = 0;
+        if (!get()) {
+            data_ = &NullChar_;
+            length_ = 0;
+            ownsChars_ = false;
+        }
+    }
+
     const char16_t* data_;
     size_t length_;
     bool ownsChars_;
diff --git a/js/xpconnect/loader/ChromeScriptLoader.cpp b/js/xpconnect/loader/ChromeScriptLoader.cpp
index faeb90acb892..5f2f26e4f276 100644
--- a/js/xpconnect/loader/ChromeScriptLoader.cpp
+++ b/js/xpconnect/loader/ChromeScriptLoader.cpp
@@ -131,8 +131,7 @@ AsyncScriptCompiler::StartCompile(JSContext* aCx)
 {
     Rooted<JSObject*> global(aCx, mGlobalObject->GetGlobalJSObject());
 
-    JS::SourceBufferHolder srcBuf(mScriptText.get(), mScriptLength,
-                                  JS::SourceBufferHolder::NoOwnership);
+    JS::SourceBufferHolder srcBuf(std::move(mScriptText), mScriptLength);
     if (JS::CanCompileOffThread(aCx, mOptions, mScriptLength)) {
         if (!JS::CompileOffThread(aCx, mOptions, srcBuf,
                                   OffThreadScriptLoaderCallback,