diff --git a/.github/workflows/cross.sh b/.github/workflows/cross.sh
index e447b6f..2c138b8 100755
--- a/.github/workflows/cross.sh
+++ b/.github/workflows/cross.sh
@@ -18,12 +18,8 @@ echo js            ; GOOS=js        GOARCH=wasm  go build .
 echo wasip1        ; GOOS=wasip1    GOARCH=wasm  go build .
 echo linux-flock   ; GOOS=linux     GOARCH=amd64 go build -tags sqlite3_flock .
 echo linux-dotlk   ; GOOS=linux     GOARCH=amd64 go build -tags sqlite3_dotlk .
-echo linux-nosys   ; GOOS=linux     GOARCH=amd64 go build -tags sqlite3_nosys .
 echo darwin-flock  ; GOOS=darwin    GOARCH=amd64 go build -tags sqlite3_flock .
 echo darwin-dotlk  ; GOOS=darwin    GOARCH=amd64 go build -tags sqlite3_dotlk .
-echo darwin-nosys  ; GOOS=darwin    GOARCH=amd64 go build -tags sqlite3_nosys .
 echo windows-dotlk ; GOOS=windows   GOARCH=amd64 go build -tags sqlite3_dotlk .
-echo windows-nosys ; GOOS=windows   GOARCH=amd64 go build -tags sqlite3_nosys .
 echo freebsd-dotlk ; GOOS=freebsd   GOARCH=amd64 go build -tags sqlite3_dotlk .
-echo freebsd-nosys ; GOOS=freebsd   GOARCH=amd64 go build -tags sqlite3_nosys .
 echo solaris-dotlk ; GOOS=solaris   GOARCH=amd64 go build -tags sqlite3_dotlk .
\ No newline at end of file
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 0cc5788..857f76f 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -54,10 +54,6 @@ jobs:
     - name: Test
       run: go test -v ./... -bench . -benchtime=1x
 
-    - name: Test no locks
-      run: go test -v -tags sqlite3_nosys ./...
-      if: matrix.os == 'ubuntu-latest'
-
     - name: Test BSD locks
       run: go test -v -tags sqlite3_flock ./...
       if: matrix.os == 'macos-latest'
diff --git a/driver/example2_test.go b/driver/example2_test.go
index 15aa815..7e70530 100644
--- a/driver/example2_test.go
+++ b/driver/example2_test.go
@@ -1,4 +1,4 @@
-//go:build (linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock) && !sqlite3_nosys
+//go:build linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock || sqlite3_dotlk
 
 package driver_test
 
diff --git a/driver/example_test.go b/driver/example_test.go
index 1e04050..68ec74f 100644
--- a/driver/example_test.go
+++ b/driver/example_test.go
@@ -1,4 +1,4 @@
-//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock || sqlite3_dotlk
 
 package driver_test
 
diff --git a/internal/alloc/alloc_other.go b/internal/alloc/alloc_other.go
index d9a3de2..b420acc 100644
--- a/internal/alloc/alloc_other.go
+++ b/internal/alloc/alloc_other.go
@@ -1,4 +1,4 @@
-//go:build !(unix || windows) || sqlite3_nosys
+//go:build !unix && !windows
 
 package alloc
 
diff --git a/internal/alloc/alloc_unix.go b/internal/alloc/alloc_unix.go
index 2948487..a00dbbf 100644
--- a/internal/alloc/alloc_unix.go
+++ b/internal/alloc/alloc_unix.go
@@ -1,4 +1,4 @@
-//go:build unix && !sqlite3_nosys
+//go:build unix
 
 package alloc
 
diff --git a/internal/alloc/alloc_windows.go b/internal/alloc/alloc_windows.go
index 8e67e03..6bfc73a 100644
--- a/internal/alloc/alloc_windows.go
+++ b/internal/alloc/alloc_windows.go
@@ -1,5 +1,3 @@
-//go:build !sqlite3_nosys
-
 package alloc
 
 import (
diff --git a/internal/util/mmap_other.go b/internal/util/mmap_other.go
index e11f953..720977b 100644
--- a/internal/util/mmap_other.go
+++ b/internal/util/mmap_other.go
@@ -1,4 +1,4 @@
-//go:build !unix || sqlite3_nosys
+//go:build !unix
 
 package util
 
diff --git a/internal/util/mmap.go b/internal/util/mmap_unix.go
similarity index 98%
rename from internal/util/mmap.go
rename to internal/util/mmap_unix.go
index 613bb90..5d5ca38 100644
--- a/internal/util/mmap.go
+++ b/internal/util/mmap_unix.go
@@ -1,4 +1,4 @@
-//go:build unix && !sqlite3_nosys
+//go:build unix
 
 package util
 
diff --git a/internal/util/mmap_windows.go b/internal/util/mmap_windows.go
index fdf6f43..efff1e7 100644
--- a/internal/util/mmap_windows.go
+++ b/internal/util/mmap_windows.go
@@ -1,5 +1,3 @@
-//go:build !sqlite3_nosys
-
 package util
 
 import (
diff --git a/tests/bradfitz/sql_test.go b/tests/bradfitz/sql_test.go
index d7e2b3b..dc86207 100644
--- a/tests/bradfitz/sql_test.go
+++ b/tests/bradfitz/sql_test.go
@@ -1,4 +1,4 @@
-//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock || sqlite3_dotlk
 
 package bradfitz
 
diff --git a/vfs/README.md b/vfs/README.md
index 0877797..354f8bf 100644
--- a/vfs/README.md
+++ b/vfs/README.md
@@ -91,7 +91,6 @@ The implementation is compatible with SQLite's
 The VFS can be customized with a few build tags:
 - `sqlite3_flock` forces the use of BSD locks.
 - `sqlite3_dotlk` forces the use of dot-file locks.
-- `sqlite3_nosys` prevents importing [`x/sys`](https://pkg.go.dev/golang.org/x/sys).
 
 > [!IMPORTANT]
 > The default configuration of this package is compatible with the standard
diff --git a/vfs/adiantum/example_test.go b/vfs/adiantum/example_test.go
index d4da01a..5d10edb 100644
--- a/vfs/adiantum/example_test.go
+++ b/vfs/adiantum/example_test.go
@@ -1,4 +1,4 @@
-//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock || sqlite3_dotlk
 
 package adiantum_test
 
diff --git a/vfs/lock.go b/vfs/lock.go
index 22e320a..8828662 100644
--- a/vfs/lock.go
+++ b/vfs/lock.go
@@ -1,4 +1,4 @@
-//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock || sqlite3_dotlk
 
 package vfs
 
diff --git a/vfs/lock_other.go b/vfs/lock_other.go
index 81aacc6..9bdfa3c 100644
--- a/vfs/lock_other.go
+++ b/vfs/lock_other.go
@@ -1,4 +1,4 @@
-//go:build !(((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk)
+//go:build !(linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos || sqlite3_flock || sqlite3_dotlk)
 
 package vfs
 
diff --git a/vfs/os_bsd.go b/vfs/os_bsd.go
index cc5da7c..fa13ef3 100644
--- a/vfs/os_bsd.go
+++ b/vfs/os_bsd.go
@@ -1,4 +1,4 @@
-//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && !(sqlite3_dotlk || sqlite3_nosys)) || sqlite3_flock
+//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && !sqlite3_dotlk) || sqlite3_flock
 
 package vfs
 
diff --git a/vfs/os_darwin.go b/vfs/os_darwin.go
index c8d84dc..7d809b2 100644
--- a/vfs/os_darwin.go
+++ b/vfs/os_darwin.go
@@ -1,4 +1,4 @@
-//go:build !(sqlite3_flock || sqlite3_nosys)
+//go:build !sqlite3_flock
 
 package vfs
 
diff --git a/vfs/os_f2fs_linux.go b/vfs/os_f2fs_linux.go
index 07bf0a0..3661430 100644
--- a/vfs/os_f2fs_linux.go
+++ b/vfs/os_f2fs_linux.go
@@ -1,4 +1,4 @@
-//go:build (amd64 || arm64 || riscv64) && !sqlite3_nosys
+//go:build amd64 || arm64 || riscv64
 
 package vfs
 
diff --git a/vfs/os_linux.go b/vfs/os_linux.go
index e163e80..f5841fc 100644
--- a/vfs/os_linux.go
+++ b/vfs/os_linux.go
@@ -1,4 +1,4 @@
-//go:build !(sqlite3_flock || sqlite3_nosys)
+//go:build !sqlite3_flock
 
 package vfs
 
diff --git a/vfs/os_ofd.go b/vfs/os_ofd.go
index b4f570f..d93050e 100644
--- a/vfs/os_ofd.go
+++ b/vfs/os_ofd.go
@@ -1,4 +1,4 @@
-//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_dotlk || sqlite3_nosys)
+//go:build (linux || darwin) && !(sqlite3_flock || sqlite3_dotlk)
 
 package vfs
 
diff --git a/vfs/os_std.go b/vfs/os_std.go
index 87ce58b..a17893d 100644
--- a/vfs/os_std.go
+++ b/vfs/os_std.go
@@ -1,4 +1,4 @@
-//go:build !unix || sqlite3_nosys
+//go:build !unix
 
 package vfs
 
diff --git a/vfs/os_std_alloc.go b/vfs/os_std_alloc.go
index 60c9218..4dd1bb3 100644
--- a/vfs/os_std_alloc.go
+++ b/vfs/os_std_alloc.go
@@ -1,4 +1,4 @@
-//go:build !(linux || darwin) || sqlite3_flock || sqlite3_nosys
+//go:build !(linux || darwin) || sqlite3_flock
 
 package vfs
 
diff --git a/vfs/os_std_atomic.go b/vfs/os_std_atomic.go
index ecaff02..10a0c84 100644
--- a/vfs/os_std_atomic.go
+++ b/vfs/os_std_atomic.go
@@ -1,4 +1,4 @@
-//go:build !linux || !(amd64 || arm64 || riscv64) || sqlite3_nosys
+//go:build !linux || !(amd64 || arm64 || riscv64)
 
 package vfs
 
diff --git a/vfs/os_std_sync.go b/vfs/os_std_sync.go
index 84dbd23..b32e83e 100644
--- a/vfs/os_std_sync.go
+++ b/vfs/os_std_sync.go
@@ -1,4 +1,4 @@
-//go:build !(linux || darwin) || sqlite3_flock || sqlite3_nosys
+//go:build !(linux || darwin) || sqlite3_flock
 
 package vfs
 
diff --git a/vfs/os_unix.go b/vfs/os_unix.go
index 7a54088..6637c29 100644
--- a/vfs/os_unix.go
+++ b/vfs/os_unix.go
@@ -1,4 +1,4 @@
-//go:build unix && !sqlite3_nosys
+//go:build unix
 
 package vfs
 
diff --git a/vfs/os_unix_test.go b/vfs/os_unix_test.go
index ad430ab..21e5cd3 100644
--- a/vfs/os_unix_test.go
+++ b/vfs/os_unix_test.go
@@ -1,4 +1,4 @@
-//go:build unix && !(sqlite3_flock || sqlite3_nosys)
+//go:build unix && !sqlite3_flock
 
 package vfs
 
diff --git a/vfs/os_windows.go b/vfs/os_windows.go
index 0b6e5d3..2d4342e 100644
--- a/vfs/os_windows.go
+++ b/vfs/os_windows.go
@@ -1,4 +1,4 @@
-//go:build !(sqlite3_dotlk || sqlite3_nosys)
+//go:build !sqlite3_dotlk
 
 package vfs
 
diff --git a/vfs/shm.go b/vfs/shm.go
index 9d9dff1..f289552 100644
--- a/vfs/shm.go
+++ b/vfs/shm.go
@@ -1,4 +1,4 @@
-//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build ((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le)) || sqlite3_flock || sqlite3_dotlk
 
 package vfs
 
diff --git a/vfs/shm_bsd.go b/vfs/shm_bsd.go
index 07cabf7..e4850ab 100644
--- a/vfs/shm_bsd.go
+++ b/vfs/shm_bsd.go
@@ -1,4 +1,4 @@
-//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_dotlk || sqlite3_nosys)) || sqlite3_flock
+//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_dotlk) || sqlite3_flock
 
 package vfs
 
diff --git a/vfs/shm_copy.go b/vfs/shm_copy.go
index bc02983..db8ddb4 100644
--- a/vfs/shm_copy.go
+++ b/vfs/shm_copy.go
@@ -1,4 +1,4 @@
-//go:build (windows && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys) || sqlite3_dotlk
+//go:build (windows && (386 || arm || amd64 || arm64 || riscv64 || ppc64le)) || sqlite3_dotlk
 
 package vfs
 
diff --git a/vfs/shm_memlk.go b/vfs/shm_memlk.go
index dc7b913..4040196 100644
--- a/vfs/shm_memlk.go
+++ b/vfs/shm_memlk.go
@@ -1,4 +1,4 @@
-//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk
+//go:build ((freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le)) || sqlite3_flock || sqlite3_dotlk
 
 package vfs
 
diff --git a/vfs/shm_ofd.go b/vfs/shm_ofd.go
index 75c8fbc..08d0382 100644
--- a/vfs/shm_ofd.go
+++ b/vfs/shm_ofd.go
@@ -1,4 +1,4 @@
-//go:build (linux || darwin) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_flock || sqlite3_dotlk || sqlite3_nosys)
+//go:build (linux || darwin) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_flock || sqlite3_dotlk)
 
 package vfs
 
diff --git a/vfs/shm_other.go b/vfs/shm_other.go
index 9602dd0..69319f0 100644
--- a/vfs/shm_other.go
+++ b/vfs/shm_other.go
@@ -1,4 +1,4 @@
-//go:build !(((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_nosys) || sqlite3_flock || sqlite3_dotlk)
+//go:build !(((linux || darwin || windows || freebsd || openbsd || netbsd || dragonfly || illumos) && (386 || arm || amd64 || arm64 || riscv64 || ppc64le)) || sqlite3_flock || sqlite3_dotlk)
 
 package vfs
 
diff --git a/vfs/shm_windows.go b/vfs/shm_windows.go
index 374d491..4c9bad5 100644
--- a/vfs/shm_windows.go
+++ b/vfs/shm_windows.go
@@ -1,4 +1,4 @@
-//go:build (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !(sqlite3_dotlk || sqlite3_nosys)
+//go:build (386 || arm || amd64 || arm64 || riscv64 || ppc64le) && !sqlite3_dotlk
 
 package vfs