diff --git a/pymbolic/sympy_conv.py b/pymbolic/sympy_conv.py
index 049131c9da35e81f9250c60419cfe9d264f24c6e..079a14acde9d80a88d96019d0484b7f7fddad9ee 100644
--- a/pymbolic/sympy_conv.py
+++ b/pymbolic/sympy_conv.py
@@ -34,13 +34,32 @@ class _SympyMapper(object):
 
 
 
-class ToPymbolicMapper(_SympyMapper):
+class CSE(sp.Function):
+    """A function to translate to a Pymbolic CSE."""
+
+    nargs = 1
+
+
+
+
+def make_cse(arg, prefix=None):
+    result = CSE(arg)
+    result.prefix = prefix
+    return result
+
+
+
+
+class SympyToPymbolicMapper(_SympyMapper):
     def map_Symbol(self, expr):
         return prim.Variable(expr.name)
 
     def map_ImaginaryUnit(self, expr):
         return 1j
 
+    def map_Pi(self, expr):
+        return float(expr)
+
     def map_Add(self, expr):
         return prim.Sum(tuple(self.rec(arg) for arg in expr.args))
 
@@ -68,6 +87,10 @@ class ToPymbolicMapper(_SympyMapper):
         return prim.Derivative(self.rec(expr.expr),
                 tuple(v.name for v in expr.variables))
 
+    def map_CSE(self, expr):
+        return prim.CommonSubexpression(
+                self.rec(expr.args[0]), expr.prefix)
+
     def not_supported(self, expr):
         if isinstance(expr, int):
             return expr