diff --git a/.travis.yml b/.travis.yml
index d60f684..6fed8a2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,3 +16,4 @@ install: true
 script:
   - make validation
   - make validation.tags
+  - make build.arches
diff --git a/Makefile b/Makefile
index 071de49..231326c 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,7 @@ CWD := $(shell pwd)
 SOURCE_FILES := $(shell find . -type f -name "*.go")
 CLEAN_FILES := *~
 TAGS := cvis
+ARCHES := linux,386 linux,amd64 linux,arm linux,arm64 openbsd,amd64 windows,amd64 darwin,amd64
 
 default: build validation 
 
@@ -60,6 +61,20 @@ build: $(BUILD)
 $(BUILD): $(SOURCE_FILES)
 	go build ./cmd/$(BUILD)
 
+./bin:
+	mkdir -p $@
+
+CLEAN_FILES += bin
+
+build.arches: ./bin
+	@set -e ;\
+	for pair in $(ARCHES); do \
+	p=$$(echo $$pair | cut -d , -f 1);\
+	a=$$(echo $$pair | cut -d , -f 2);\
+	echo "Building $$p/$$a ...";\
+	GOOS=$$p GOARCH=$$a go build -o ./bin/gomtree.$$p.$$a ./cmd/gomtree/ ;\
+	done
+
 clean:
 	rm -rf $(BUILD) $(CLEAN_FILES)
 
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
 	}
 )