diff --git a/README.md b/README.md
index c3f8d15..9804793 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 
 This is very much a WIP.
 
-TODO:
+Roadmap:
 - [x] build SQLite using `zig cc --target=wasm32-wasi`
 - [x] `:memory:` databases
 - [x] use [`test_demovfs.c`](sqlite3/test_demovfs.c) for file databases
@@ -13,6 +13,7 @@ TODO:
     - [`github.com/bvinc/go-sqlite-lite`](https://github.com/bvinc/go-sqlite-lite)
     - [`github.com/crawshaw/sqlite`](https://github.com/crawshaw/sqlite)
     - [`github.com/zombiezen/go-sqlite`](https://github.com/zombiezen/go-sqlite)
+    - [`github.com/cvilsmeier/sqinn-go`](https://github.com/cvilsmeier/sqinn-go)
   - [`database/sql`](https://pkg.go.dev/database/sql) drivers can come later, if ever
 - [ ] implement own VFS to sidestep WASI syscalls:
   - locking will be a pain point:
@@ -21,6 +22,14 @@ TODO:
     - file access needs to be synchronized, both in-process and out-of-process
     - out-of-process should be compatible with SQLite on Windows/Unix
 - [ ] benchmark to see if this is usefull at all:
+  - [`github.com/cvilsmeier/sqinn-go`](https://github.com/cvilsmeier/sqinn-go-bench)
   - [`github.com/bvinc/go-sqlite-lite`](https://github.com/bvinc/go-sqlite-lite)
   - [`github.com/mattn/go-sqlite3`](https://github.com/mattn/go-sqlite3)
   - [`modernc.org/sqlite`](https://modernc.org/sqlite)
+
+Random TODO list:
+- wrap more of the SQLite API, enough to run useful queries;
+- create a Go VFS that's enough to use `:memory:` databases without WASI;
+- expand that VFS to wrap an `io.ReaderAt`;
+- optimize small allocations that last a single function call;
+- …
\ No newline at end of file
diff --git a/build_deps.sh b/build_deps.sh
index f2c1062..e4a3510 100755
--- a/build_deps.sh
+++ b/build_deps.sh
@@ -44,6 +44,5 @@ zig cc --target=wasm32-wasi -flto -g0 -O2 \
 	-Wl,--export=sqlite3_errstr \
 	-Wl,--export=sqlite3_errmsg \
 	-Wl,--export=sqlite3_error_offset \
-	-Wl,--export=sqlite3_extended_errcode \
 	-Wl,--export=malloc \
 	-Wl,--export=free
diff --git a/cmd/main.go b/cmd/main.go
index 1c33bb3..a517408 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -8,7 +8,7 @@ import (
 )
 
 func main() {
-	db, err := sqlite3.Open(":memory:", 0, "")
+	db, err := sqlite3.Open(":memory:")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -23,7 +23,7 @@ func main() {
 		log.Fatal(err)
 	}
 
-	stmt, _, err := db.Prepare(`SELECT id, name FROM users`, 0)
+	stmt, _, err := db.Prepare(`SELECT id, name FROM users`)
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/conn.go b/conn.go
index 3a6c249..08c9a0d 100644
--- a/conn.go
+++ b/conn.go
@@ -19,7 +19,11 @@ type Conn struct {
 	api    sqliteAPI
 }
 
-func Open(name string, flags uint64, vfs string) (conn *Conn, err error) {
+func Open(name string) (conn *Conn, err error) {
+	return OpenFlags(name, OPEN_READWRITE|OPEN_CREATE)
+}
+
+func OpenFlags(name string, flags OpenFlag) (conn *Conn, err error) {
 	once.Do(compile)
 
 	var fs fs.FS
@@ -53,7 +57,6 @@ func Open(name string, flags uint64, vfs string) (conn *Conn, err error) {
 			errstr:      module.ExportedFunction("sqlite3_errstr"),
 			errmsg:      module.ExportedFunction("sqlite3_errmsg"),
 			erroff:      module.ExportedFunction("sqlite3_error_offset"),
-			errext:      module.ExportedFunction("sqlite3_extended_errcode"),
 			open:        module.ExportedFunction("sqlite3_open_v2"),
 			close:       module.ExportedFunction("sqlite3_close"),
 			prepare:     module.ExportedFunction("sqlite3_prepare_v3"),
@@ -75,16 +78,7 @@ func Open(name string, flags uint64, vfs string) (conn *Conn, err error) {
 	namePtr := c.newString(name)
 	connPtr := c.newBytes(ptrSize)
 
-	if flags == 0 {
-		flags = OPEN_READWRITE | OPEN_CREATE
-	}
-
-	var vfsPtr uint32
-	if vfs != "" {
-		vfsPtr = c.newString(vfs)
-	}
-
-	r, err := c.api.open.Call(ctx, uint64(namePtr), uint64(connPtr), flags, uint64(vfsPtr))
+	r, err := c.api.open.Call(ctx, uint64(namePtr), uint64(connPtr), uint64(flags), 0)
 	if err != nil {
 		return nil, err
 	}
@@ -92,9 +86,8 @@ func Open(name string, flags uint64, vfs string) (conn *Conn, err error) {
 	c.handle, _ = c.memory.ReadUint32Le(connPtr)
 	c.free(connPtr)
 	c.free(namePtr)
-	c.free(vfsPtr)
 
-	if r[0] != OK {
+	if r[0] != _OK {
 		return nil, c.error(r[0])
 	}
 	return &c, nil
@@ -106,7 +99,7 @@ func (c *Conn) Close() error {
 		return err
 	}
 
-	if r[0] != OK {
+	if r[0] != _OK {
 		return c.error(r[0])
 	}
 	return c.module.Close(context.TODO())
@@ -122,19 +115,23 @@ func (c *Conn) Exec(sql string) error {
 
 	c.free(sqlPtr)
 
-	if r[0] != OK {
+	if r[0] != _OK {
 		return c.error(r[0])
 	}
 	return nil
 }
 
-func (c *Conn) Prepare(sql string, flags uint64, args ...any) (stmt *Stmt, tail string, err error) {
+func (c *Conn) Prepare(sql string) (stmt *Stmt, tail string, err error) {
+	return c.PrepareFlags(sql, 0)
+}
+
+func (c *Conn) PrepareFlags(sql string, flags PrepareFlag) (stmt *Stmt, tail string, err error) {
 	sqlPtr := c.newString(sql)
 	stmtPtr := c.newBytes(ptrSize)
 	tailPtr := c.newBytes(ptrSize)
 
 	r, err := c.api.prepare.Call(context.TODO(), uint64(c.handle),
-		uint64(sqlPtr), uint64(len(sql)+1), flags,
+		uint64(sqlPtr), uint64(len(sql)+1), uint64(flags),
 		uint64(stmtPtr), uint64(tailPtr))
 	if err != nil {
 		return nil, "", err
@@ -149,7 +146,7 @@ func (c *Conn) Prepare(sql string, flags uint64, args ...any) (stmt *Stmt, tail
 	c.free(stmtPtr)
 	c.free(sqlPtr)
 
-	if r[0] != OK {
+	if r[0] != _OK {
 		return nil, "", c.error(r[0])
 	}
 	if stmt.handle == 0 {
@@ -159,12 +156,15 @@ func (c *Conn) Prepare(sql string, flags uint64, args ...any) (stmt *Stmt, tail
 }
 
 func (c *Conn) error(rc uint64) *Error {
-	serr := Error{Code: int(rc)}
+	serr := Error{
+		Code:         ErrorCode(rc & 0xFF),
+		ExtendedCode: ExtendedErrorCode(rc),
+	}
 
 	var r []uint64
 
 	// string
-	r, _ = c.api.errstr.Call(context.TODO(), uint64(rc))
+	r, _ = c.api.errstr.Call(context.TODO(), rc)
 	if r != nil {
 		serr.str = c.getString(uint32(r[0]), 512)
 	}
@@ -175,12 +175,6 @@ func (c *Conn) error(rc uint64) *Error {
 		serr.msg = c.getString(uint32(r[0]), 512)
 	}
 
-	// extended code
-	r, _ = c.api.errext.Call(context.TODO(), uint64(c.handle))
-	if r != nil {
-		serr.ExtendedCode = int(r[0])
-	}
-
 	if serr.str == serr.msg {
 		serr.msg = ""
 	}
@@ -247,7 +241,6 @@ type sqliteAPI struct {
 	free        api.Function
 	errstr      api.Function
 	errmsg      api.Function
-	errext      api.Function
 	erroff      api.Function
 	open        api.Function
 	close       api.Function
diff --git a/const.go b/const.go
index f064bc6..09e5727 100644
--- a/const.go
+++ b/const.go
@@ -1,12 +1,153 @@
 package sqlite3
 
 const (
-	OK   = 0
-	ROW  = 100
-	DONE = 101
+	_OK   = 0   /* Successful result */
+	_ROW  = 100 /* sqlite3_step() has another row ready */
+	_DONE = 101 /* sqlite3_step() has finished executing */
 )
 
+type ErrorCode int
+
 const (
-	OPEN_READWRITE = 0x00000002
-	OPEN_CREATE    = 0x00000004
+	ERROR      ErrorCode = 1  /* Generic error */
+	INTERNAL   ErrorCode = 2  /* Internal logic error in SQLite */
+	PERM       ErrorCode = 3  /* Access permission denied */
+	ABORT      ErrorCode = 4  /* Callback routine requested an abort */
+	BUSY       ErrorCode = 5  /* The database file is locked */
+	LOCKED     ErrorCode = 6  /* A table in the database is locked */
+	NOMEM      ErrorCode = 7  /* A malloc() failed */
+	READONLY   ErrorCode = 8  /* Attempt to write a readonly database */
+	INTERRUPT  ErrorCode = 9  /* Operation terminated by sqlite3_interrupt()*/
+	IOERR      ErrorCode = 10 /* Some kind of disk I/O error occurred */
+	CORRUPT    ErrorCode = 11 /* The database disk image is malformed */
+	NOTFOUND   ErrorCode = 12 /* Unknown opcode in sqlite3_file_control() */
+	FULL       ErrorCode = 13 /* Insertion failed because database is full */
+	CANTOPEN   ErrorCode = 14 /* Unable to open the database file */
+	PROTOCOL   ErrorCode = 15 /* Database lock protocol error */
+	EMPTY      ErrorCode = 16 /* Internal use only */
+	SCHEMA     ErrorCode = 17 /* The database schema changed */
+	TOOBIG     ErrorCode = 18 /* String or BLOB exceeds size limit */
+	CONSTRAINT ErrorCode = 19 /* Abort due to constraint violation */
+	MISMATCH   ErrorCode = 20 /* Data type mismatch */
+	MISUSE     ErrorCode = 21 /* Library used incorrectly */
+	NOLFS      ErrorCode = 22 /* Uses OS features not supported on host */
+	AUTH       ErrorCode = 23 /* Authorization denied */
+	FORMAT     ErrorCode = 24 /* Not used */
+	RANGE      ErrorCode = 25 /* 2nd parameter to sqlite3_bind out of range */
+	NOTADB     ErrorCode = 26 /* File opened that is not a database file */
+	NOTICE     ErrorCode = 27 /* Notifications from sqlite3_log() */
+	WARNING    ErrorCode = 28 /* Warnings from sqlite3_log() */
+)
+
+type ExtendedErrorCode int
+
+const (
+	ERROR_MISSING_COLLSEQ   = ExtendedErrorCode(ERROR | (1 << 8))
+	ERROR_RETRY             = ExtendedErrorCode(ERROR | (2 << 8))
+	ERROR_SNAPSHOT          = ExtendedErrorCode(ERROR | (3 << 8))
+	IOERR_READ              = ExtendedErrorCode(IOERR | (1 << 8))
+	IOERR_SHORT_READ        = ExtendedErrorCode(IOERR | (2 << 8))
+	IOERR_WRITE             = ExtendedErrorCode(IOERR | (3 << 8))
+	IOERR_FSYNC             = ExtendedErrorCode(IOERR | (4 << 8))
+	IOERR_DIR_FSYNC         = ExtendedErrorCode(IOERR | (5 << 8))
+	IOERR_TRUNCATE          = ExtendedErrorCode(IOERR | (6 << 8))
+	IOERR_FSTAT             = ExtendedErrorCode(IOERR | (7 << 8))
+	IOERR_UNLOCK            = ExtendedErrorCode(IOERR | (8 << 8))
+	IOERR_RDLOCK            = ExtendedErrorCode(IOERR | (9 << 8))
+	IOERR_DELETE            = ExtendedErrorCode(IOERR | (10 << 8))
+	IOERR_BLOCKED           = ExtendedErrorCode(IOERR | (11 << 8))
+	IOERR_NOMEM             = ExtendedErrorCode(IOERR | (12 << 8))
+	IOERR_ACCESS            = ExtendedErrorCode(IOERR | (13 << 8))
+	IOERR_CHECKRESERVEDLOCK = ExtendedErrorCode(IOERR | (14 << 8))
+	IOERR_LOCK              = ExtendedErrorCode(IOERR | (15 << 8))
+	IOERR_CLOSE             = ExtendedErrorCode(IOERR | (16 << 8))
+	IOERR_DIR_CLOSE         = ExtendedErrorCode(IOERR | (17 << 8))
+	IOERR_SHMOPEN           = ExtendedErrorCode(IOERR | (18 << 8))
+	IOERR_SHMSIZE           = ExtendedErrorCode(IOERR | (19 << 8))
+	IOERR_SHMLOCK           = ExtendedErrorCode(IOERR | (20 << 8))
+	IOERR_SHMMAP            = ExtendedErrorCode(IOERR | (21 << 8))
+	IOERR_SEEK              = ExtendedErrorCode(IOERR | (22 << 8))
+	IOERR_DELETE_NOENT      = ExtendedErrorCode(IOERR | (23 << 8))
+	IOERR_MMAP              = ExtendedErrorCode(IOERR | (24 << 8))
+	IOERR_GETTEMPPATH       = ExtendedErrorCode(IOERR | (25 << 8))
+	IOERR_CONVPATH          = ExtendedErrorCode(IOERR | (26 << 8))
+	IOERR_VNODE             = ExtendedErrorCode(IOERR | (27 << 8))
+	IOERR_AUTH              = ExtendedErrorCode(IOERR | (28 << 8))
+	IOERR_BEGIN_ATOMIC      = ExtendedErrorCode(IOERR | (29 << 8))
+	IOERR_COMMIT_ATOMIC     = ExtendedErrorCode(IOERR | (30 << 8))
+	IOERR_ROLLBACK_ATOMIC   = ExtendedErrorCode(IOERR | (31 << 8))
+	IOERR_DATA              = ExtendedErrorCode(IOERR | (32 << 8))
+	IOERR_CORRUPTFS         = ExtendedErrorCode(IOERR | (33 << 8))
+	LOCKED_SHAREDCACHE      = ExtendedErrorCode(LOCKED | (1 << 8))
+	LOCKED_VTAB             = ExtendedErrorCode(LOCKED | (2 << 8))
+	BUSY_RECOVERY           = ExtendedErrorCode(BUSY | (1 << 8))
+	BUSY_SNAPSHOT           = ExtendedErrorCode(BUSY | (2 << 8))
+	BUSY_TIMEOUT            = ExtendedErrorCode(BUSY | (3 << 8))
+	CANTOPEN_NOTEMPDIR      = ExtendedErrorCode(CANTOPEN | (1 << 8))
+	CANTOPEN_ISDIR          = ExtendedErrorCode(CANTOPEN | (2 << 8))
+	CANTOPEN_FULLPATH       = ExtendedErrorCode(CANTOPEN | (3 << 8))
+	CANTOPEN_CONVPATH       = ExtendedErrorCode(CANTOPEN | (4 << 8))
+	CANTOPEN_DIRTYWAL       = ExtendedErrorCode(CANTOPEN | (5 << 8)) /* Not Used */
+	CANTOPEN_SYMLINK        = ExtendedErrorCode(CANTOPEN | (6 << 8))
+	CORRUPT_VTAB            = ExtendedErrorCode(CORRUPT | (1 << 8))
+	CORRUPT_SEQUENCE        = ExtendedErrorCode(CORRUPT | (2 << 8))
+	CORRUPT_INDEX           = ExtendedErrorCode(CORRUPT | (3 << 8))
+	READONLY_RECOVERY       = ExtendedErrorCode(READONLY | (1 << 8))
+	READONLY_CANTLOCK       = ExtendedErrorCode(READONLY | (2 << 8))
+	READONLY_ROLLBACK       = ExtendedErrorCode(READONLY | (3 << 8))
+	READONLY_DBMOVED        = ExtendedErrorCode(READONLY | (4 << 8))
+	READONLY_CANTINIT       = ExtendedErrorCode(READONLY | (5 << 8))
+	READONLY_DIRECTORY      = ExtendedErrorCode(READONLY | (6 << 8))
+	ABORT_ROLLBACK          = ExtendedErrorCode(ABORT | (2 << 8))
+	CONSTRAINT_CHECK        = ExtendedErrorCode(CONSTRAINT | (1 << 8))
+	CONSTRAINT_COMMITHOOK   = ExtendedErrorCode(CONSTRAINT | (2 << 8))
+	CONSTRAINT_FOREIGNKEY   = ExtendedErrorCode(CONSTRAINT | (3 << 8))
+	CONSTRAINT_FUNCTION     = ExtendedErrorCode(CONSTRAINT | (4 << 8))
+	CONSTRAINT_NOTNULL      = ExtendedErrorCode(CONSTRAINT | (5 << 8))
+	CONSTRAINT_PRIMARYKEY   = ExtendedErrorCode(CONSTRAINT | (6 << 8))
+	CONSTRAINT_TRIGGER      = ExtendedErrorCode(CONSTRAINT | (7 << 8))
+	CONSTRAINT_UNIQUE       = ExtendedErrorCode(CONSTRAINT | (8 << 8))
+	CONSTRAINT_VTAB         = ExtendedErrorCode(CONSTRAINT | (9 << 8))
+	CONSTRAINT_ROWID        = ExtendedErrorCode(CONSTRAINT | (10 << 8))
+	CONSTRAINT_PINNED       = ExtendedErrorCode(CONSTRAINT | (11 << 8))
+	CONSTRAINT_DATATYPE     = ExtendedErrorCode(CONSTRAINT | (12 << 8))
+	NOTICE_RECOVER_WAL      = ExtendedErrorCode(NOTICE | (1 << 8))
+	NOTICE_RECOVER_ROLLBACK = ExtendedErrorCode(NOTICE | (2 << 8))
+	WARNING_AUTOINDEX       = ExtendedErrorCode(WARNING | (1 << 8))
+	AUTH_USER               = ExtendedErrorCode(AUTH | (1 << 8))
+)
+
+type OpenFlag uint
+
+const (
+	OPEN_READONLY      OpenFlag = 0x00000001 /* Ok for sqlite3_open_v2() */
+	OPEN_READWRITE     OpenFlag = 0x00000002 /* Ok for sqlite3_open_v2() */
+	OPEN_CREATE        OpenFlag = 0x00000004 /* Ok for sqlite3_open_v2() */
+	OPEN_DELETEONCLOSE OpenFlag = 0x00000008 /* VFS only */
+	OPEN_EXCLUSIVE     OpenFlag = 0x00000010 /* VFS only */
+	OPEN_AUTOPROXY     OpenFlag = 0x00000020 /* VFS only */
+	OPEN_URI           OpenFlag = 0x00000040 /* Ok for sqlite3_open_v2() */
+	OPEN_MEMORY        OpenFlag = 0x00000080 /* Ok for sqlite3_open_v2() */
+	OPEN_MAIN_DB       OpenFlag = 0x00000100 /* VFS only */
+	OPEN_TEMP_DB       OpenFlag = 0x00000200 /* VFS only */
+	OPEN_TRANSIENT_DB  OpenFlag = 0x00000400 /* VFS only */
+	OPEN_MAIN_JOURNAL  OpenFlag = 0x00000800 /* VFS only */
+	OPEN_TEMP_JOURNAL  OpenFlag = 0x00001000 /* VFS only */
+	OPEN_SUBJOURNAL    OpenFlag = 0x00002000 /* VFS only */
+	OPEN_SUPER_JOURNAL OpenFlag = 0x00004000 /* VFS only */
+	OPEN_NOMUTEX       OpenFlag = 0x00008000 /* Ok for sqlite3_open_v2() */
+	OPEN_FULLMUTEX     OpenFlag = 0x00010000 /* Ok for sqlite3_open_v2() */
+	OPEN_SHAREDCACHE   OpenFlag = 0x00020000 /* Ok for sqlite3_open_v2() */
+	OPEN_PRIVATECACHE  OpenFlag = 0x00040000 /* Ok for sqlite3_open_v2() */
+	OPEN_WAL           OpenFlag = 0x00080000 /* VFS only */
+	OPEN_NOFOLLOW      OpenFlag = 0x01000000 /* Ok for sqlite3_open_v2() */
+	OPEN_EXRESCODE     OpenFlag = 0x02000000 /* Extended result codes */
+)
+
+type PrepareFlag uint
+
+const (
+	PREPARE_PERSISTENT PrepareFlag = 0x01
+	PREPARE_NORMALIZE  PrepareFlag = 0x02
+	PREPARE_NO_VTAB    PrepareFlag = 0x04
 )
diff --git a/error.go b/error.go
index e492eb9..36b5158 100644
--- a/error.go
+++ b/error.go
@@ -6,8 +6,8 @@ import (
 )
 
 type Error struct {
-	Code         int
-	ExtendedCode int
+	Code         ErrorCode
+	ExtendedCode ExtendedErrorCode
 	str          string
 	msg          string
 }
@@ -19,7 +19,7 @@ func (e Error) Error() string {
 	if e.str != "" {
 		b.WriteString(e.str)
 	} else {
-		b.WriteString(strconv.Itoa(e.Code))
+		b.WriteString(strconv.Itoa(int(e.Code)))
 	}
 
 	if e.msg != "" {
diff --git a/stmt.go b/stmt.go
index 90d1b5e..f311802 100644
--- a/stmt.go
+++ b/stmt.go
@@ -14,7 +14,7 @@ func (s *Stmt) Close() error {
 	}
 
 	s.handle = 0
-	if r[0] != OK {
+	if r[0] != _OK {
 		return s.c.error(r[0])
 	}
 	return nil