diff --git a/dom/base/nsScriptLoader.cpp b/dom/base/nsScriptLoader.cpp
index 6c732db6ca..a6d20e363c 100644
--- a/dom/base/nsScriptLoader.cpp
+++ b/dom/base/nsScriptLoader.cpp
@@ -2630,7 +2630,10 @@ nsScriptLoader::PrepareLoadedRequest(nsScriptLoadRequest* aRequest,
     }
 
     nsAutoCString sourceMapURL;
-    rv = httpChannel->GetResponseHeader(NS_LITERAL_CSTRING("X-SourceMap"), sourceMapURL);
+    rv = httpChannel->GetResponseHeader(NS_LITERAL_CSTRING("SourceMap"), sourceMapURL);
+    if (NS_FAILED(rv)) {
+      rv = httpChannel->GetResponseHeader(NS_LITERAL_CSTRING("X-SourceMap"), sourceMapURL);
+    }
     if (NS_SUCCEEDED(rv)) {
       aRequest->mHasSourceMapURL = true;
       aRequest->mSourceMapURL = NS_ConvertUTF8toUTF16(sourceMapURL);