diff --git a/keywords_unsupported.go b/keywords_unsupported.go
index aba791b..e890ccb 100644
--- a/keywords_unsupported.go
+++ b/keywords_unsupported.go
@@ -10,28 +10,32 @@ import (
 )
 
 var (
-	unameKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (string, error) {
+	// this is bsd specific https://www.freebsd.org/cgi/man.cgi?query=chflags&sektion=2
+	flagsKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (KeyVal, error) {
+		return emptyKV, nil
+	}
+	unameKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (KeyVal, error) {
 		if hdr, ok := info.Sys().(*tar.Header); ok {
-			return fmt.Sprintf("uname=%s", hdr.Uname), nil
+			return KeyVal(fmt.Sprintf("uname=%s", hdr.Uname)), nil
 		}
-		return "", nil
+		return emptyKV, nil
 	}
-	uidKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (string, error) {
+	uidKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (KeyVal, error) {
 		if hdr, ok := info.Sys().(*tar.Header); ok {
-			return fmt.Sprintf("uid=%d", hdr.Uid), nil
+			return KeyVal(fmt.Sprintf("uid=%d", hdr.Uid)), nil
 		}
-		return "", nil
+		return emptyKV, nil
 	}
-	gidKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (string, error) {
+	gidKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (KeyVal, error) {
 		if hdr, ok := info.Sys().(*tar.Header); ok {
-			return fmt.Sprintf("gid=%d", hdr.Gid), nil
+			return KeyVal(fmt.Sprintf("gid=%d", hdr.Gid)), nil
 		}
-		return "", nil
+		return emptyKV, nil
 	}
-	nlinkKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (string, error) {
-		return "", nil
+	nlinkKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (KeyVal, error) {
+		return emptyKV, nil
 	}
-	xattrKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (string, error) {
-		return "", nil
+	xattrKeywordFunc = func(path string, info os.FileInfo, r io.Reader) (KeyVal, error) {
+		return emptyKV, nil
 	}
 )