diff -r e1b1be597736 Lib/sqlite3/test/regression.py
--- a/Lib/sqlite3/test/regression.py	Tue Sep 09 19:07:49 2014 +0300
+++ b/Lib/sqlite3/test/regression.py	Tue Sep 09 20:53:46 2014 +0300
@@ -336,6 +336,16 @@
                           sqlite.connect, ":memory:", isolation_level=123)
 
 
+    def CheckNullCharacter(self):
+        # Issue #21147
+        con = sqlite.connect(":memory:")
+        self.assertRaises(ValueError, con, "\0select 1")
+        self.assertRaises(ValueError, con, "select 1\0")
+        cur = con.cursor()
+        self.assertRaises(ValueError, cur.execute, " \0select 2")
+        self.assertRaises(ValueError, cur.execute, "select 2\0")
+
+
 def suite():
     regression_suite = unittest.makeSuite(RegressionTests, "Check")
     return unittest.TestSuite((regression_suite,))
diff -r e1b1be597736 Modules/_sqlite/connection.c
--- a/Modules/_sqlite/connection.c	Tue Sep 09 19:07:49 2014 +0300
+++ b/Modules/_sqlite/connection.c	Tue Sep 09 20:53:46 2014 +0300
@@ -1261,7 +1261,8 @@
         if (rc == PYSQLITE_TOO_MUCH_SQL) {
             PyErr_SetString(pysqlite_Warning, "You can only execute one statement at a time.");
         } else if (rc == PYSQLITE_SQL_WRONG_TYPE) {
-            PyErr_SetString(pysqlite_Warning, "SQL is of wrong type. Must be string or unicode.");
+            if (PyErr_ExceptionMatches(PyExc_TypeError))
+                PyErr_SetString(pysqlite_Warning, "SQL is of wrong type. Must be string.");
         } else {
             (void)pysqlite_statement_reset(statement);
             _pysqlite_seterror(self->db, NULL);
diff -r e1b1be597736 Modules/_sqlite/statement.c
--- a/Modules/_sqlite/statement.c	Tue Sep 09 19:07:49 2014 +0300
+++ b/Modules/_sqlite/statement.c	Tue Sep 09 20:53:46 2014 +0300
@@ -63,6 +63,10 @@
         rc = PYSQLITE_SQL_WRONG_TYPE;
         return rc;
     }
+    if (strlen(sql_cstr) != (size_t)sql_cstr_len) {
+        PyErr_SetString(PyExc_ValueError, "the query contains a null character");
+        return PYSQLITE_SQL_WRONG_TYPE;
+    }
 
     self->in_weakreflist = NULL;
     Py_INCREF(sql);