diff --git a/env_unix.go b/env-tomap.go
similarity index 56%
rename from env_unix.go
rename to env-tomap.go
index 411d438..80fcea0 100644
--- a/env_unix.go
+++ b/env-tomap.go
@@ -1,5 +1,4 @@
-//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
-// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+//go:build !windows
 
 package env
 
diff --git a/env_unix_test.go b/env-tomap_test.go
similarity index 93%
rename from env_unix_test.go
rename to env-tomap_test.go
index 3998f26..2f7840c 100644
--- a/env_unix_test.go
+++ b/env-tomap_test.go
@@ -1,3 +1,5 @@
+//go:build !windows
+
 package env
 
 import "testing"
diff --git a/env_windows.go b/env-tomap_windows.go
similarity index 96%
rename from env_windows.go
rename to env-tomap_windows.go
index e12123c..43b8502 100644
--- a/env_windows.go
+++ b/env-tomap_windows.go
@@ -1,3 +1,5 @@
+//go:build windows
+
 package env
 
 import "strings"
diff --git a/env_windows_test.go b/env-tomap_windows_test.go
similarity index 96%
rename from env_windows_test.go
rename to env-tomap_windows_test.go
index ccca2be..d54262e 100644
--- a/env_windows_test.go
+++ b/env-tomap_windows_test.go
@@ -1,3 +1,5 @@
+//go:build windows
+
 package env
 
 import "testing"