diff --git a/lib/extras.py b/lib/extras.py
index 1aad3d1d..80034e6f 100644
--- a/lib/extras.py
+++ b/lib/extras.py
@@ -1232,10 +1232,50 @@ def execute_values(cur, sql, argslist, template=None, page_size=100):
         [(1, 20, 3), (4, 50, 6), (7, 8, 9)])
 
     '''
+    # we can't just use sql % vals because vals is bytes: if sql is bytes
+    # there will be some decoding error because of stupid codec used, and Py3
+    # doesn't implement % on bytes.
+    if not isinstance(sql, bytes):
+        sql = sql.encode(_ext.encodings[cur.connection.encoding])
+    pre, post = _split_sql(sql)
+
     for page in _paginate(argslist, page_size=page_size):
         if template is None:
             template = '(%s)' % ','.join(['%s'] * len(page[0]))
-        values = b",".join(cur.mogrify(template, args) for args in page)
-        if isinstance(values, bytes):
-            values = values.decode(_ext.encodings[cur.connection.encoding])
-        cur.execute(sql % (values,))
+        parts = [pre]
+        for args in page:
+            parts.append(cur.mogrify(template, args))
+            parts.append(b',')
+        parts[-1] = post
+        cur.execute(b''.join(parts))
+
+
+def _split_sql(sql):
+    """Split *sql* on a single ``%s`` placeholder.
+
+    Return a (pre, post) pair around the ``%s``, with ``%%`` -> ``%`` replacement.
+    """
+    curr = pre = []
+    post = []
+    tokens = _re.split(br'(%.)', sql)
+    for token in tokens:
+        if len(token) != 2 or token[:1] != b'%':
+            curr.append(token)
+            continue
+
+        if token[1:] == b's':
+            if curr is pre:
+                curr = post
+            else:
+                raise ValueError(
+                    "the query contains more than one '%s' placeholder")
+        elif token[1:] == b'%':
+            curr.append(b'%')
+        else:
+            raise ValueError("unsupported format character: '%s'"
+                % token[1:].decode('ascii', 'replace'))
+
+    if curr is pre:
+        raise ValueError("the query doesn't contain any '%s' placeholder")
+
+    return b''.join(pre), b''.join(post)
diff --git a/tests/__init__.py b/tests/__init__.py
index 1a240994..35837e82 100755
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -37,6 +37,7 @@ import test_cursor
 import test_dates
 import test_errcodes
 import test_extras_dictcursor
+import test_fast_executemany
 import test_green
 import test_ipaddress
 import test_lobject
@@ -74,6 +75,7 @@ def test_suite():
     suite.addTest(test_dates.test_suite())
     suite.addTest(test_errcodes.test_suite())
     suite.addTest(test_extras_dictcursor.test_suite())
+    suite.addTest(test_fast_executemany.test_suite())
     suite.addTest(test_green.test_suite())
     suite.addTest(test_ipaddress.test_suite())
     suite.addTest(test_lobject.test_suite())
diff --git a/tests/test_fast_executemany.py b/tests/test_fast_executemany.py
new file mode 100755
index 00000000..92222748
--- /dev/null
+++ b/tests/test_fast_executemany.py
@@ -0,0 +1,237 @@
+#!/usr/bin/env python
+#
+# test_fast_executemany.py - tests for fast executemany implementations
+#
+# Copyright (C) 2017 Daniele Varrazzo  <daniele.varrazzo@gmail.com>
+#
+# psycopg2 is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Lesser General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# psycopg2 is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
+# License for more details.
+
+import unittest
+from datetime import date
+
+from testutils import ConnectingTestCase
+
+import psycopg2
+import psycopg2.extras
+import psycopg2.extensions as ext
+
+
+class TestPaginate(unittest.TestCase):
+    def test_paginate(self):
+        def pag(seq):
+            return psycopg2.extras._paginate(seq, 100)
+
+        self.assertEqual(list(pag([])), [])
+        self.assertEqual(list(pag([1])), [[1]])
+        self.assertEqual(list(pag(range(99))), [list(range(99))])
+        self.assertEqual(list(pag(range(100))), [list(range(100))])
+        self.assertEqual(list(pag(range(101))), [list(range(100)), [100]])
+        self.assertEqual(
+            list(pag(range(200))), [list(range(100)), list(range(100, 200))])
+        self.assertEqual(
+            list(pag(range(1000))),
+            [list(range(i * 100, (i + 1) * 100)) for i in range(10)])
+
+
+class FastExecuteTestMixin(object):
+    def setUp(self):
+        super(FastExecuteTestMixin, self).setUp()
+        cur = self.conn.cursor()
+        cur.execute("""create table testfast (
+            id serial primary key, date date, val int, data text)""")
+
+
+class TestExecuteBatch(FastExecuteTestMixin, ConnectingTestCase):
+    def test_empty(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, val) values (%s, %s)",
+            [])
+        cur.execute("select * from testfast order by id")
+        self.assertEqual(cur.fetchall(), [])
+
+    def test_one(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, val) values (%s, %s)",
+            iter([(1, 10)]))
+        cur.execute("select id, val from testfast order by id")
+        self.assertEqual(cur.fetchall(), [(1, 10)])
+
+    def test_tuples(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, date, val) values (%s, %s, %s)",
+            ((i, date(2017, 1, i + 1), i * 10) for i in range(10)))
+        cur.execute("select id, date, val from testfast order by id")
+        self.assertEqual(cur.fetchall(),
+            [(i, date(2017, 1, i + 1), i * 10) for i in range(10)])
+
+    def test_many(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, val) values (%s, %s)",
+            ((i, i * 10) for i in range(1000)))
+        cur.execute("select id, val from testfast order by id")
+        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(1000)])
+
+    def test_pages(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, val) values (%s, %s)",
+            ((i, i * 10) for i in range(25)),
+            page_size=10)
+
+        # last command was 5 statements
+        self.assertEqual(sum(c == u';' for c in cur.query.decode('ascii')), 4)
+
+        cur.execute("select id, val from testfast order by id")
+        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(25)])
+
+    def test_unicode(self):
+        cur = self.conn.cursor()
+        ext.register_type(ext.UNICODE, cur)
+        snowman = u"\u2603"
+
+        # unicode in statement
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, data) values (%%s, %%s) -- %s" % snowman,
+            [(1, 'x')])
+        cur.execute("select id, data from testfast where id = 1")
+        self.assertEqual(cur.fetchone(), (1, 'x'))
+
+        # unicode in data
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, data) values (%s, %s)",
+            [(2, snowman)])
+        cur.execute("select id, data from testfast where id = 2")
+        self.assertEqual(cur.fetchone(), (2, snowman))
+
+        # unicode in both
+        psycopg2.extras.execute_batch(cur,
+            "insert into testfast (id, data) values (%%s, %%s) -- %s" % snowman,
+            [(3, snowman)])
+        cur.execute("select id, data from testfast where id = 3")
+        self.assertEqual(cur.fetchone(), (3, snowman))
+
+
+class TestExecuteValuse(FastExecuteTestMixin, ConnectingTestCase):
+    def test_empty(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, val) values %s",
+            [])
+        cur.execute("select * from testfast order by id")
+        self.assertEqual(cur.fetchall(), [])
+
+    def test_one(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, val) values %s",
+            iter([(1, 10)]))
+        cur.execute("select id, val from testfast order by id")
+        self.assertEqual(cur.fetchall(), [(1, 10)])
+
+    def test_tuples(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, date, val) values %s",
+            ((i, date(2017, 1, i + 1), i * 10) for i in range(10)))
+        cur.execute("select id, date, val from testfast order by id")
+        self.assertEqual(cur.fetchall(),
+            [(i, date(2017, 1, i + 1), i * 10) for i in range(10)])
+
+    def test_dicts(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, date, val) values %s",
+            (dict(id=i, date=date(2017, 1, i + 1), val=i * 10, foo="bar")
+                for i in range(10)),
+            template='(%(id)s, %(date)s, %(val)s)')
+        cur.execute("select id, date, val from testfast order by id")
+        self.assertEqual(cur.fetchall(),
+            [(i, date(2017, 1, i + 1), i * 10) for i in range(10)])
+
+    def test_many(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, val) values %s",
+            ((i, i * 10) for i in range(1000)))
+        cur.execute("select id, val from testfast order by id")
+        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(1000)])
+
+    def test_pages(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, val) values %s",
+            ((i, i * 10) for i in range(25)),
+            page_size=10)
+
+        # last statement was 5 tuples (one parens is for the fields list)
+        self.assertEqual(sum(c == '(' for c in cur.query.decode('ascii')), 6)
+
+        cur.execute("select id, val from testfast order by id")
+        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(25)])
+
+    def test_unicode(self):
+        cur = self.conn.cursor()
+        ext.register_type(ext.UNICODE, cur)
+        snowman = u"\u2603"
+
+        # unicode in statement
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, data) values %%s -- %s" % snowman,
+            [(1, 'x')])
+        cur.execute("select id, data from testfast where id = 1")
+        self.assertEqual(cur.fetchone(), (1, 'x'))
+
+        # unicode in data
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, data) values %s",
+            [(2, snowman)])
+        cur.execute("select id, data from testfast where id = 2")
+        self.assertEqual(cur.fetchone(), (2, snowman))
+
+        # unicode in both
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, data) values %%s -- %s" % snowman,
+            [(3, snowman)])
+        cur.execute("select id, data from testfast where id = 3")
+        self.assertEqual(cur.fetchone(), (3, snowman))
+
+    def test_invalid_sql(self):
+        cur = self.conn.cursor()
+        self.assertRaises(ValueError, psycopg2.extras.execute_values, cur,
+            "insert", [])
+        self.assertRaises(ValueError, psycopg2.extras.execute_values, cur,
+            "insert %s and %s", [])
+        self.assertRaises(ValueError, psycopg2.extras.execute_values, cur,
+            "insert %f", [])
+        self.assertRaises(ValueError, psycopg2.extras.execute_values, cur,
+            "insert %f %s", [])
+
+    def test_percent_escape(self):
+        cur = self.conn.cursor()
+        psycopg2.extras.execute_values(cur,
+            "insert into testfast (id, data) values %s -- a%%b",
+            [(1, 'hi')])
+        self.assert_(b'a%%b' not in cur.query)
+        self.assert_(b'a%b' in cur.query)
+
+        cur.execute("select id, data from testfast")
+        self.assertEqual(cur.fetchall(), [(1, 'hi')])
+
+
+def test_suite():
+    return unittest.TestLoader().loadTestsFromName(__name__)
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/test_types_extras.py b/tests/test_types_extras.py
index a584c868..8e615616 100755
--- a/tests/test_types_extras.py
+++ b/tests/test_types_extras.py
@@ -1766,184 +1766,6 @@ class RangeCasterTestCase(ConnectingTestCase):
 decorate_all_tests(RangeCasterTestCase, skip_if_no_range)
 
 
-class TestFastExecute(ConnectingTestCase):
-    def setUp(self):
-        super(TestFastExecute, self).setUp()
-        cur = self.conn.cursor()
-        cur.execute("""create table testfast (
-            id serial primary key, date date, val int, data text)""")
-
-    def test_paginate(self):
-        def pag(seq):
-            return psycopg2.extras._paginate(seq, 100)
-
-        self.assertEqual(list(pag([])), [])
-        self.assertEqual(list(pag([1])), [[1]])
-        self.assertEqual(list(pag(range(99))), [list(range(99))])
-        self.assertEqual(list(pag(range(100))), [list(range(100))])
-        self.assertEqual(list(pag(range(101))), [list(range(100)), [100]])
-        self.assertEqual(
-            list(pag(range(200))), [list(range(100)), list(range(100, 200))])
-        self.assertEqual(
-            list(pag(range(1000))),
-            [list(range(i * 100, (i + 1) * 100)) for i in range(10)])
-
-    def test_execute_batch_empty(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, val) values (%s, %s)",
-            [])
-        cur.execute("select * from testfast order by id")
-        self.assertEqual(cur.fetchall(), [])
-
-    def test_execute_batch_one(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, val) values (%s, %s)",
-            iter([(1, 10)]))
-        cur.execute("select id, val from testfast order by id")
-        self.assertEqual(cur.fetchall(), [(1, 10)])
-
-    def test_execute_batch_tuples(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, date, val) values (%s, %s, %s)",
-            ((i, date(2017, 1, i + 1), i * 10) for i in range(10)))
-        cur.execute("select id, date, val from testfast order by id")
-        self.assertEqual(cur.fetchall(),
-            [(i, date(2017, 1, i + 1), i * 10) for i in range(10)])
-
-    def test_execute_batch_many(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, val) values (%s, %s)",
-            ((i, i * 10) for i in range(1000)))
-        cur.execute("select id, val from testfast order by id")
-        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(1000)])
-
-    def test_execute_batch_pages(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, val) values (%s, %s)",
-            ((i, i * 10) for i in range(25)),
-            page_size=10)
-
-        # last command was 5 statements
-        self.assertEqual(sum(c == u';' for c in cur.query.decode('ascii')), 4)
-
-        cur.execute("select id, val from testfast order by id")
-        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(25)])
-
-    def test_execute_batch_unicode(self):
-        cur = self.conn.cursor()
-        ext.register_type(ext.UNICODE, cur)
-        snowman = u"\u2603"
-
-        # unicode in statement
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, data) values (%%s, %%s) -- %s" % snowman,
-            [(1, 'x')])
-        cur.execute("select id, data from testfast where id = 1")
-        self.assertEqual(cur.fetchone(), (1, 'x'))
-
-        # unicode in data
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, data) values (%s, %s)",
-            [(2, snowman)])
-        cur.execute("select id, data from testfast where id = 2")
-        self.assertEqual(cur.fetchone(), (2, snowman))
-
-        # unicode in both
-        psycopg2.extras.execute_batch(cur,
-            "insert into testfast (id, data) values (%%s, %%s) -- %s" % snowman,
-            [(3, snowman)])
-        cur.execute("select id, data from testfast where id = 3")
-        self.assertEqual(cur.fetchone(), (3, snowman))
-
-    def test_execute_values_empty(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, val) values %s",
-            [])
-        cur.execute("select * from testfast order by id")
-        self.assertEqual(cur.fetchall(), [])
-
-    def test_execute_values_one(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, val) values %s",
-            iter([(1, 10)]))
-        cur.execute("select id, val from testfast order by id")
-        self.assertEqual(cur.fetchall(), [(1, 10)])
-
-    def test_execute_values_tuples(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, date, val) values %s",
-            ((i, date(2017, 1, i + 1), i * 10) for i in range(10)))
-        cur.execute("select id, date, val from testfast order by id")
-        self.assertEqual(cur.fetchall(),
-            [(i, date(2017, 1, i + 1), i * 10) for i in range(10)])
-
-    def test_execute_values_dicts(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, date, val) values %s",
-            (dict(id=i, date=date(2017, 1, i + 1), val=i * 10, foo="bar")
-                for i in range(10)),
-            template='(%(id)s, %(date)s, %(val)s)')
-        cur.execute("select id, date, val from testfast order by id")
-        self.assertEqual(cur.fetchall(),
-            [(i, date(2017, 1, i + 1), i * 10) for i in range(10)])
-
-    def test_execute_values_many(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, val) values %s",
-            ((i, i * 10) for i in range(1000)))
-        cur.execute("select id, val from testfast order by id")
-        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(1000)])
-
-    def test_execute_values_pages(self):
-        cur = self.conn.cursor()
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, val) values %s",
-            ((i, i * 10) for i in range(25)),
-            page_size=10)
-
-        # last statement was 5 tuples (one parens is for the fields list)
-        self.assertEqual(sum(c == '(' for c in cur.query.decode('ascii')), 6)
-
-        cur.execute("select id, val from testfast order by id")
-        self.assertEqual(cur.fetchall(), [(i, i * 10) for i in range(25)])
-
-    def test_execute_values_unicode(self):
-        cur = self.conn.cursor()
-        ext.register_type(ext.UNICODE, cur)
-        snowman = u"\u2603"
-
-        # unicode in statement
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, data) values %%s -- %s" % snowman,
-            [(1, 'x')])
-        cur.execute("select id, data from testfast where id = 1")
-        self.assertEqual(cur.fetchone(), (1, 'x'))
-
-        # unicode in data
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, data) values %s",
-            [(2, snowman)])
-        cur.execute("select id, data from testfast where id = 2")
-        self.assertEqual(cur.fetchone(), (2, snowman))
-
-        # unicode in both
-        psycopg2.extras.execute_values(cur,
-            "insert into testfast (id, data) values %%s -- %s" % snowman,
-            [(3, snowman)])
-        cur.execute("select id, data from testfast where id = 3")
-        self.assertEqual(cur.fetchone(), (3, snowman))
-
-
 def test_suite():
     return unittest.TestLoader().loadTestsFromName(__name__)