diff --git a/anki/latex.py b/anki/latex.py
index 9793c55fc..4b1913b68 100644
--- a/anki/latex.py
+++ b/anki/latex.py
@@ -78,11 +78,11 @@ def _buildImg(col, latex, fname, model):
     latex = latex.encode("utf8")
     # it's only really secure if run in a jail, but these are the most common
     tmplatex = latex.replace("\\includegraphics", "")
-    for bad in ("write18", "\\\\readline", "\\\\input", "\\\\include",
-                "\\\\catcode", "\\\\openout", "\\\\write", "\\\\loop",
-                "\\\\def", "\\\\shipout"):
+    for bad in ("\\write18", "\\readline", "\\input", "\\include",
+                "\\catcode", "\\openout", "\\write", "\\loop",
+                "\\def", "\\shipout"):
         # don't mind if the sequence is only part of a command
-        bad_re = bad + "[^a-zA-Z]"
+        bad_re = "\\" + bad + "[^a-zA-Z]"
         if re.search(bad_re, tmplatex):
             return _("""\
 For security reasons, '%s' is not allowed on cards. You can still use \