diff --git a/README.md b/README.md
index b27f921..95aa201 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,6 @@ This project intends to provide a well-tested and maintainable alternative to
 
 - Python 3 (>=3.6)
 - Python dependencies:
-  - apsw
   - jinja2
   
 ## Usage
diff --git a/matemat/db/facade.py b/matemat/db/facade.py
index 106c792..8dd8e93 100644
--- a/matemat/db/facade.py
+++ b/matemat/db/facade.py
@@ -7,6 +7,7 @@ from hmac import compare_digest
 from matemat.primitives import User, Product
 from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
 from matemat.db import DatabaseWrapper
+from matemat.db.wrapper import Transaction
 
 # TODO: Change to METHOD_BLOWFISH when adopting Python 3.7
 """
@@ -50,19 +51,19 @@ class MatematDatabase(object):
         # Pass context manager stuff through to the database wrapper
         self.db.__exit__(exc_type, exc_val, exc_tb)
 
-    def transaction(self, exclusive: bool = True) -> Any:
+    def transaction(self, exclusive: bool = True) -> Transaction:
         """
-        Begin a new SQLite3 transaction (exclusive by default).  You should never need to use the returned object (an
-        APSW cursor).  It is provided in case there is a real need for it (e.g. for unit testing).
+        Begin a new SQLite3 transaction (exclusive by default).  You should never need to use the returned object (a
+        Transaction instance).  It is provided in case there is a real need for it (e.g. for unit testing).
 
-        This function should be used with the Context Manager 'with' syntax (PEP 343), e.g.:
+        This function should be used with the Context Manager 'with' syntax (PEP 343), yielding a sqlite3.Cursor, e.g.:
 
         with db.transaction():
             db.foo()
             db.bar()
 
         :param exclusive: Whether to begin an exclusive transaction or not, defaults to True (exclusive).
-        :return: An APSW cursor.
+        :return: A a transaction object.
         """
         return self.db.transaction(exclusive=exclusive)
 
diff --git a/matemat/db/test/test_wrapper.py b/matemat/db/test/test_wrapper.py
index dafff65..e5a52c2 100644
--- a/matemat/db/test/test_wrapper.py
+++ b/matemat/db/test/test_wrapper.py
@@ -75,3 +75,29 @@ class DatabaseTest(unittest.TestCase):
             c = db._sqlite_db.cursor()
             c.execute("SELECT * FROM users")
             self.assertIsNone(c.fetchone())
+
+    def test_connect_twice(self):
+        """
+        If a connection is already established, a RuntimeError should be raised when attempting to connect a
+        second time.
+        """
+        self.db.connect()
+        with self.assertRaises(RuntimeError):
+            self.db.connect()
+        self.db.close()
+
+    def test_close_not_opened(self):
+        """
+        Attempting to close an unopened connection should raise a RuntimeError.
+        """
+        with self.assertRaises(RuntimeError):
+            self.db.close()
+
+    def test_close_in_transaction(self):
+        """
+        Attempting to close a connection inside a transaction should raise a RuntimeError.
+        """
+        with self.db as db:
+            with db.transaction():
+                with self.assertRaises(RuntimeError):
+                    self.db.close()
diff --git a/matemat/db/wrapper.py b/matemat/db/wrapper.py
index 509dade..e930d17 100644
--- a/matemat/db/wrapper.py
+++ b/matemat/db/wrapper.py
@@ -1,43 +1,40 @@
 
 from typing import Any
 
-import apsw
+import sqlite3
 
 from matemat.exceptions import DatabaseConsistencyError
 
 
 class Transaction(object):
 
-    def __init__(self, db: apsw.Connection, wrapper: 'DatabaseWrapper', exclusive: bool = True) -> None:
-        self._db: apsw.Connection = db
+    def __init__(self, db: sqlite3.Connection, exclusive: bool = True) -> None:
+        self._db: sqlite3.Connection = db
         self._cursor = None
         self._excl = exclusive
-        self._wrapper: DatabaseWrapper = wrapper
         self._is_dummy: bool = False
 
-    def __enter__(self) -> Any:
-        if self._wrapper._in_transaction:
+    def __enter__(self) -> sqlite3.Cursor:
+        if self._db.in_transaction:
             self._is_dummy = True
             return self._db.cursor()
         else:
             self._is_dummy = False
-        self._cursor = self._db.cursor()
-        self._wrapper._in_transaction = True
         if self._excl:
-            self._cursor.execute('BEGIN EXCLUSIVE')
+            self._db.execute('BEGIN EXCLUSIVE')
         else:
-            self._cursor.execute('BEGIN')
+            self._db.execute('BEGIN')
+        self._cursor = self._db.cursor()
         return self._cursor
 
     def __exit__(self, exc_type: Any, exc_val: Any, exc_tb: Any) -> None:
         if self._is_dummy:
             return
         if exc_type is None:
-            self._cursor.execute('COMMIT')
+            self._db.commit()
         else:
-            self._cursor.execute('ROLLBACK')
-        self._wrapper._in_transaction = False
-        if exc_type == apsw.ConstraintError:
+            self._db.rollback()
+        if exc_type == sqlite3.IntegrityError:
             raise DatabaseConsistencyError(str(exc_val))
 
 
@@ -47,7 +44,7 @@ class DatabaseWrapper(object):
     SCHEMA = '''
     CREATE TABLE users (
       user_id INTEGER PRIMARY KEY,
-      username TEXT NOT NULL,
+      username TEXT UNIQUE NOT NULL,
       email TEXT DEFAULT NULL,
       password TEXT NOT NULL,
       touchkey TEXT DEFAULT NULL,
@@ -72,13 +69,12 @@ class DatabaseWrapper(object):
         ON DELETE CASCADE ON UPDATE CASCADE,
       FOREIGN KEY (product_id) REFERENCES products(product_id)
         ON DELETE CASCADE ON UPDATE CASCADE
-    )
+    );
     '''
 
     def __init__(self, filename: str) -> None:
         self._filename: str = filename
-        self._sqlite_db: apsw.Connection = None
-        self._in_transaction: bool = False
+        self._sqlite_db: sqlite3.Connection = None
 
     def __enter__(self) -> 'DatabaseWrapper':
         self.connect()
@@ -88,13 +84,13 @@ class DatabaseWrapper(object):
         self.close()
 
     def transaction(self, exclusive: bool = True) -> Transaction:
-        return Transaction(self._sqlite_db, self, exclusive)
+        return Transaction(self._sqlite_db, exclusive)
 
     def _setup(self) -> None:
         with self.transaction() as c:
             version: int = self._user_version
             if version < 1:
-                c.execute(self.SCHEMA)
+                c.executescript(self.SCHEMA)
             elif version < self.SCHEMA_VERSION:
                 self._upgrade(old=version, new=self.SCHEMA_VERSION)
             self._user_version = self.SCHEMA_VERSION
@@ -105,7 +101,7 @@ class DatabaseWrapper(object):
     def connect(self) -> None:
         if self.is_connected():
             raise RuntimeError(f'Database connection to {self._filename} is already established.')
-        self._sqlite_db = apsw.Connection(self._filename)
+        self._sqlite_db = sqlite3.connect(self._filename)
         self._setup()
 
     def close(self) -> None:
@@ -117,7 +113,7 @@ class DatabaseWrapper(object):
         self._sqlite_db = None
 
     def in_transaction(self) -> bool:
-        return self._in_transaction
+        return self._sqlite_db.in_transaction
 
     def is_connected(self) -> bool:
         return self._sqlite_db is not None
diff --git a/requirements.txt b/requirements.txt
index 7663204..7f7afbf 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,2 +1 @@
-apsw
 jinja2