diff --git a/cuburn/code/iter.py b/cuburn/code/iter.py
index fb837c6..f444bff 100644
--- a/cuburn/code/iter.py
+++ b/cuburn/code/iter.py
@@ -118,6 +118,10 @@ void apply_xf{{xfid}}(float &ox, float &oy, float &color, mwc_st &rctx) {
     }
     {{endfor}}
 
+    {{if xform.has_post}}
+    tx = ox;
+    ty = oy;
+    {{apply_affine_flam3('tx', 'ty', 'ox', 'oy', px, 'xf.post', 'post')}}
     {{endif}}
 
     float csp = {{px.get('xf.color_speed')}};
diff --git a/cuburn/render.py b/cuburn/render.py
index 13a591b..717a24e 100644
--- a/cuburn/render.py
+++ b/cuburn/render.py
@@ -458,9 +458,15 @@ class XFormFeatures(object):
     def __init__(self, xforms, xform_id):
         self.id = xform_id
         any = lambda l: bool(filter(None, map(l, xforms)))
-        self.has_post = any(lambda xf: getattr(xf, 'post', None))
+
+        self.has_post = any(lambda xf: not self.id_matrix(xf.post))
         self.vars = set()
         for x in xforms:
             self.vars = (
                 self.vars.union(set([i for i, v in enumerate(x.var) if v])))
 
+    @staticmethod
+    def id_matrix(m):
+        return (m[0][0] == 1 and m[1][0] == 0 and m[2][0] == 0 and
+                m[0][1] == 0 and m[1][1] == 1 and m[2][1] == 0)
+