diff --git a/dom/encoding/TextDecoder.cpp b/dom/encoding/TextDecoder.cpp
index b214799e5aec..120dd7d4ab7e 100644
--- a/dom/encoding/TextDecoder.cpp
+++ b/dom/encoding/TextDecoder.cpp
@@ -206,6 +206,13 @@ TextDecoder::GetEncoding(nsAString& aEncoding)
     return;
   }
 
+  // Similarly, "x-windows-949" is used for the "euc-kr" family. Therefore, if
+  // the internal encoding name is "x-windows-949", "euc-kr" is returned.
+  if (mEncoding.EqualsLiteral("x-windows-949")) {
+    aEncoding.AssignLiteral("euc-kr");
+    return;
+  }
+
   CopyASCIItoUTF16(mEncoding, aEncoding);
   nsContentUtils::ASCIIToLower(aEncoding);
 }
diff --git a/dom/encoding/labelsencodings.properties b/dom/encoding/labelsencodings.properties
index 8a67615c7e9e..3ceecdca1ce0 100644
--- a/dom/encoding/labelsencodings.properties
+++ b/dom/encoding/labelsencodings.properties
@@ -205,16 +205,16 @@ shift_jis=Shift_JIS
 sjis=Shift_JIS
 windows-31j=Shift_JIS
 x-sjis=Shift_JIS
-cseuckr=EUC-KR
-csksc56011987=EUC-KR
-euc-kr=EUC-KR
-iso-ir-149=EUC-KR
-korean=EUC-KR
-ks_c_5601-1987=EUC-KR
-ks_c_5601-1989=EUC-KR
-ksc5601=EUC-KR
-ksc_5601=EUC-KR
-windows-949=EUC-KR
+cseuckr=x-windows-949
+csksc56011987=x-windows-949
+euc-kr=x-windows-949
+iso-ir-149=x-windows-949
+korean=x-windows-949
+ks_c_5601-1987=x-windows-949
+ks_c_5601-1989=x-windows-949
+ksc5601=x-windows-949
+ksc_5601=x-windows-949
+windows-949=x-windows-949
 csiso2022kr=ISO-2022-KR
 iso-2022-kr=ISO-2022-KR
 utf-16=UTF-16LE
diff --git a/dom/encoding/test/Makefile.in b/dom/encoding/test/Makefile.in
index 36f836d0a9b6..f53c00c1f670 100644
--- a/dom/encoding/test/Makefile.in
+++ b/dom/encoding/test/Makefile.in
@@ -21,6 +21,7 @@ MOCHITEST_FILES = \
   test_TextEncoder.html \
   test_TextEncoder.js \
   test_stringencoding.html \
+  test_submit_euckr.html \
   $(NULL)
 
 MOCHITEST_CHROME_FILES = \
diff --git a/dom/encoding/test/test_submit_euckr.html b/dom/encoding/test/test_submit_euckr.html
new file mode 100644
index 000000000000..5a5b3ed82520
--- /dev/null
+++ b/dom/encoding/test/test_submit_euckr.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset=utf-8>
+  <title>Test for euc-kr encoded form submission</title>
+  <script type="text/javascript" src="/resources/testharness.js"></script>
+  <script type="text/javascript" src="/resources/testharnessreport.js"></script>
+</head>
+<body>
+<div id="log"></div>
+<iframe name="ifr"></iframe>
+<form accept-charset="euc-kr" action="abc" target="ifr">
+<input type="hidden" name="a" value="&#xAC02;">
+</form>
+<script>
+
+runTest();
+
+function runTest() {
+  var t = async_test("Test for euc-kr encoded form submission");
+  var f = document.forms[0];
+  var ifr = frames.ifr;
+  ifr.onload = function() {
+    t.step(function() {
+      assert_equals("".split.call(ifr.location, "?")[1], "a=%81A");
+    });
+    t.done();
+  };
+  f.submit();
+}
+
+</script>
+</body>
+</html>
