diff --git a/momoko/connection.py b/momoko/connection.py
index 27c12b5..dcfa164 100644
--- a/momoko/connection.py
+++ b/momoko/connection.py
@@ -752,7 +752,10 @@ def execute(self,
         """
         kwargs = {"cursor_factory": cursor_factory} if cursor_factory else {}
         cursor = self.connection.cursor(**kwargs)
-        cursor.execute(operation, parameters)
+        if parameters:
+            cursor.execute(operation, parameters)
+        else:
+            cursor.execute(operation)
 
         future = Future()
         callback = partial(self._io_callback, future, cursor)
diff --git a/tests.py b/tests.py
index e64342c..5d60ce6 100644
--- a/tests.py
+++ b/tests.py
@@ -127,6 +127,7 @@ def clean_db(self):
         yield self.conn.execute("DROP TABLE IF EXISTS unit_test_transaction;")
         yield self.conn.execute("DROP TABLE IF EXISTS  unit_test_int_table;")
         yield self.conn.execute("DROP FUNCTION IF EXISTS unit_test_callproc(integer);")
+        yield self.conn.execute("DROP FUNCTION IF EXISTS unit_test_callproc_noparams();")
 
     def prepare_db(self):
         yield self.conn.execute(
@@ -144,6 +145,12 @@ def prepare_db(self):
             "RETURN n*n;\n"
             "END;$BODY$ LANGUAGE plpgsql VOLATILE;"
         )
+        yield self.conn.execute(
+            "CREATE OR REPLACE FUNCTION unit_test_callproc_noparams()\n"
+            "RETURNS integer AS $BODY$BEGIN\n"
+            "RETURN 42;\n"
+            "END;$BODY$ LANGUAGE plpgsql VOLATILE;"
+        )
 
     def fill_int_data(self, amount=1000):
         return self.conn.transaction([
@@ -193,6 +200,15 @@ def test_execute(self):
         cursor = yield self.conn.execute("SELECT 1, 2, 3")
         self.assertEqual(cursor.fetchall(), [(1, 2, 3)])
 
+    @gen_test
+    def test_execute_percent_sign(self):
+        """
+        Testing that momoko does not complain on percent signs when there is no parameters.
+        Issue #136
+        """
+        cursor = yield self.conn.execute("SELECT 'a%s'")
+        self.assertEqual(cursor.fetchall(), [('a%s',)])
+
     @gen_test
     def test_ping(self):
         """Testing ping"""
@@ -272,6 +288,12 @@ def test_callproc(self):
         cursor = yield self.conn.callproc("unit_test_callproc", (64,))
         self.assertEqual(cursor.fetchone(), (4096,))
 
+    @gen_test
+    def test_callproc_noparams(self):
+        """Testing callproc without parameters"""
+        cursor = yield self.conn.callproc("unit_test_callproc_noparams")
+        self.assertEqual(cursor.fetchone(), (42,))
+
     @gen_test
     def test_query_error(self):
         """Testing that execute method propages exception properly"""