diff --git a/Python/compile.c b/Python/compile.c
index f90f82c..c1c2fa9 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -542,53 +542,6 @@
 	return 1;
 }
 
-/* Replace LOAD_CONST tuple with LOAD_CONST frozenset in the context
-   of a single-use constant for "in" and "not in" tests.
-*/
-int
-try_set_conversion(unsigned char *codestr, PyObject *consts)
-{
-	PyObject *newconst, *constant;
-	int arg, len_consts;
-
-	/* Pre-conditions */
-	assert(PyList_CheckExact(consts));
-	assert(codestr[0] == LOAD_CONST);
-	assert(codestr[3] == COMPARE_OP);
-	assert(GETARG(codestr, 3) == 6 || GETARG(codestr, 3) == 7);
-
-	/* Attempt to convert constant to a frozenset.  Bail-out with no
-	   changes if the tuple contains unhashable values. */
-	arg = GETARG(codestr, 0);
-	constant = PyList_GET_ITEM(consts, arg);
-	if (constant->ob_type != &PyTuple_Type)
-		return 0;
-	newconst = PyObject_CallFunctionObjArgs(
-			(PyObject *)&PyFrozenSet_Type, constant, NULL);
-	if (newconst == NULL) {
-		PyErr_Clear();
-		return 0;
-	}
-
-	/* Append new constant onto consts list or replace existing constant
-	   if there are no other references to it.*/
-	if (constant->ob_refcnt == 1) {
-		PyList_SET_ITEM(consts, arg, newconst);
-		Py_DECREF(constant);
-		return 1;
-	}
-	len_consts = PyList_GET_SIZE(consts);
-	if (PyList_Append(consts, newconst)) {
-		Py_DECREF(newconst);
-		return 0;
-	}
-	Py_DECREF(newconst);
-
-	/* Write new LOAD_CONST newconst on top of LOAD_CONST oldconst */
-	SETARG(codestr, 0, len_consts);
-	return 1;
-}
-
 static unsigned int *
 markblocks(unsigned char *code, int len)
 {
@@ -714,15 +667,10 @@
 		/* not a is b -->  a is not b
 		   not a in b -->  a not in b
 		   not a is not b -->  a is b
-		   not a not in b -->  a in b 
-		   
-		   a in c --> a in frozenset(c)
-			where c is a constant tuple of hashable values
+		   not a not in b -->  a in b
 		*/
 		case COMPARE_OP:
 			j = GETARG(codestr, i);
-			if (lastlc >= 1 && (j == 6 || j == 7) && ISBASICBLOCK(blocks,i-3,6))
-				try_set_conversion(&codestr[i-3], consts);
 			if (j < 6  ||  j > 9  ||
 			    codestr[i+3] != UNARY_NOT  || 
 			    !ISBASICBLOCK(blocks,i,4))