diff --git a/editor/libeditor/crashtests/1134545.html b/editor/libeditor/crashtests/1134545.html
new file mode 100644
index 00000000000..4e871804ff0
--- /dev/null
+++ b/editor/libeditor/crashtests/1134545.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<!-- saved from url=(0065)https://bug1134545.bugzilla.mozilla.org/attachment.cgi?id=8566418 -->
+<html><head><meta http-equiv="Content-Type" content="text/html; charset=windows-1252">
+<script>
+
+function boom()
+{
+    textNode = document.createTextNode(" ");
+    x.appendChild(textNode);
+    x.setAttribute('contenteditable', "true");
+    textNode.remove();
+    window.getSelection().selectAllChildren(textNode);
+    document.execCommand("increasefontsize", false, null);
+}
+
+</script>
+</head>
+<body onload="boom();">
+<div id="x" contenteditable="true"></div>
+
+
+</body></html>
\ No newline at end of file
diff --git a/editor/libeditor/crashtests/crashtests.list b/editor/libeditor/crashtests/crashtests.list
index 4c78bae5ec8..03b93903e53 100644
--- a/editor/libeditor/crashtests/crashtests.list
+++ b/editor/libeditor/crashtests/crashtests.list
@@ -59,3 +59,4 @@ load 772282.html
 load 776323.html
 needs-focus load 793866.html
 load 1057677.html
+load 1134545.html
diff --git a/editor/libeditor/nsHTMLEditorStyle.cpp b/editor/libeditor/nsHTMLEditorStyle.cpp
index 83065f1ef43..7a087f0fa29 100644
--- a/editor/libeditor/nsHTMLEditorStyle.cpp
+++ b/editor/libeditor/nsHTMLEditorStyle.cpp
@@ -1527,10 +1527,10 @@ nsHTMLEditor::RelativeFontChange( int32_t aSizeChange)
     int32_t offset;
     nsCOMPtr<nsINode> selectedNode;
     GetStartNodeAndOffset(selection, getter_AddRefs(selectedNode), &offset);
-    NS_ENSURE_TRUE(selectedNode, NS_OK);
-    if (IsTextNode(selectedNode)) {
+    if (selectedNode && IsTextNode(selectedNode)) {
       selectedNode = selectedNode->GetParentNode();
     }
+    NS_ENSURE_TRUE(selectedNode, NS_OK);
     if (!CanContainTag(*selectedNode, *atom)) {
       return NS_OK;
     }
