diff --git a/join.go b/join.go
deleted file mode 100644
index d1c2a53..0000000
--- a/join.go
+++ /dev/null
@@ -1,59 +0,0 @@
-//go:build !go1.20
-// +build !go1.20
-
-package errors
-
-import "unsafe"
-
-// Join returns an error that wraps the given errors.
-// Any nil error values are discarded.
-// Join returns nil if every value in errs is nil.
-// The error formats as the concatenation of the strings obtained
-// by calling the Error method of each element of errs, with a newline
-// between each string.
-//
-// A non-nil error returned by Join implements the Unwrap() []error method.
-func Join(errs ...error) error {
-	n := 0
-	for _, err := range errs {
-		if err != nil {
-			n++
-		}
-	}
-	if n == 0 {
-		return nil
-	}
-	e := &joinError{
-		errs: make([]error, 0, n),
-	}
-	for _, err := range errs {
-		if err != nil {
-			e.errs = append(e.errs, err)
-		}
-	}
-	return e
-}
-
-type joinError struct {
-	errs []error
-}
-
-func (e *joinError) Error() string {
-	// Since Join returns nil if every value in errs is nil,
-	// e.errs cannot be empty.
-	if len(e.errs) == 1 {
-		return e.errs[0].Error()
-	}
-
-	b := []byte(e.errs[0].Error())
-	for _, err := range e.errs[1:] {
-		b = append(b, '\n')
-		b = append(b, err.Error()...)
-	}
-	// At this point, b has at least one byte '\n'.
-	return unsafe.String(&b[0], len(b))
-}
-
-func (e *joinError) Unwrap() []error {
-	return e.errs
-}
diff --git a/join_go120.go b/join_go120.go
index ecf930c..575d620 100644
--- a/join_go120.go
+++ b/join_go120.go
@@ -5,4 +5,16 @@ package errors
 
 import "errors"
 
-var Join = errors.Join
+// Join returns an error that wraps the given errors.
+// Any nil error values are discarded.
+// Join returns nil if every value in errs is nil.
+// The error formats as the concatenation of the strings obtained
+// by calling the Error method of each element of errs, with a newline
+// between each string.
+//
+// A non-nil error returned by Join implements the Unwrap() []error method.
+//
+// Available only for go 1.20 or superior.
+func Join(errs ...error) error {
+	return errors.Join(errs...)
+}
diff --git a/join_test.go b/join_go120_test.go
similarity index 95%
rename from join_test.go
rename to join_go120_test.go
index bfc5667..cb8b25a 100644
--- a/join_test.go
+++ b/join_go120_test.go
@@ -1,3 +1,6 @@
+//go:build go1.20
+// +build go1.20
+
 package errors_test
 
 import (