diff --git a/editor/libeditor/html/tests/Makefile.in b/editor/libeditor/html/tests/Makefile.in
index cd86f095c1b..7f2340dfd56 100644
--- a/editor/libeditor/html/tests/Makefile.in
+++ b/editor/libeditor/html/tests/Makefile.in
@@ -81,6 +81,7 @@ MOCHITEST_FILES = \
 		test_bug767684.html \
 		test_bug780035.html \
 		test_bug787432.html \
+		test_bug790475.html \
 		test_bug796839.html \
 		test_spellcheck_pref.html \
 		$(NULL)
diff --git a/editor/libeditor/html/tests/test_bug790475.html b/editor/libeditor/html/tests/test_bug790475.html
new file mode 100644
index 00000000000..6c7d2b243c6
--- /dev/null
+++ b/editor/libeditor/html/tests/test_bug790475.html
@@ -0,0 +1,96 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=790475
+-->
+<head>
+  <title>Test for Bug 790475</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="text/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=790475">Mozilla Bug 790475</a>
+<p id="display"></p>
+<div id="content" style="display: none"></div>
+<pre id="test">
+<script type="application/javascript">
+
+/**
+ * Test for Bug 790475
+ *
+ * Tests that inline spell checking works properly through adjacent text nodes.
+ */
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(runTest);
+
+var gMisspeltWords;
+
+function getEditor() {
+  const Ci = Components.interfaces;
+  var editingSession = window.QueryInterface(Ci.nsIInterfaceRequestor)
+                             .getInterface(Ci.nsIWebNavigation)
+                             .QueryInterface(Ci.nsIInterfaceRequestor)
+                             .getInterface(Ci.nsIEditingSession);
+  return editingSession.getEditorForWindow(window);
+}
+
+function getSpellCheckSelection() {
+  var editor = getEditor();
+  var selcon = editor.selectionController;
+  return selcon.getSelection(selcon.SELECTION_SPELLCHECK);
+}
+
+function runTest() {
+  gMisspeltWords = [];
+  var edit = document.getElementById("edit");
+  edit.focus();
+
+  SimpleTest.executeSoon(function() {
+    gMisspeltWords = [];
+    is(isSpellingCheckOk(), true, "Should not find any misspellings yet.");
+
+    var newTextNode = document.createTextNode("ing string");
+    edit.appendChild(newTextNode);
+    var editor = getEditor();
+    var sel = editor.selection;
+    sel.collapse(newTextNode, newTextNode.textContent.length);
+    synthesizeKey("!", {});
+
+    edit.blur();
+
+    SimpleTest.executeSoon(function() {
+      is(isSpellingCheckOk(), true, "Should not have found any misspellings. ");
+      SimpleTest.finish();
+    });
+  });
+}
+
+function isSpellingCheckOk() {
+  netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
+
+  var sel = getSpellCheckSelection();
+  var numWords = sel.rangeCount;
+
+  is(numWords, gMisspeltWords.length, "Correct number of misspellings and words.");
+
+  if (numWords != gMisspeltWords.length)
+    return false;
+
+  for (var i = 0; i < numWords; i++) {
+    var word = sel.getRangeAt(i);
+    is (word, gMisspeltWords[i], "Misspelling is what we think it is.");
+    if (word != gMisspeltWords[i])
+      return false;
+  }
+  return true;
+}
+
+</script>
+</pre>
+
+<div id="edit" contenteditable="true">This is a test</div>
+
+</body>
+</html>
