diff --git a/Makefile b/Makefile
index 0e17ade..5fa14a1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 CC=go
-BUILD=build -v
+BUILD=build -v -trimpath
 GCFLAGS=-gcflags '-e'
 LDFLAGS=-ldflags '-s -w'
 PROGRAM=duckycode
diff --git a/README.md b/README.md
index 8013ca3..1a4c2cd 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,13 @@
 # Rubber-Ducky Encoder written in Go
 
+## Usage
 
+Encode an example:
+
+```
+./duckycode -f examples/linux.txt -l de
+```
+
+Now copy the file `inject.bin` to your microSD card.
+
+Happy Hacking.
diff --git a/go.mod b/go.mod
index e2f085e..510970b 100644
--- a/go.mod
+++ b/go.mod
@@ -1 +1,3 @@
 module git.giftfish.de/ston1th/duckycode
+
+go 1.15
diff --git a/language/ru.properties.ascii b/language/ru.properties.ascii
new file mode 100644
index 0000000..1bc124f
--- /dev/null
+++ b/language/ru.properties.ascii
@@ -0,0 +1,113 @@
+//Russian Key Map
+//http://www.charset.org/charactersets.php?charset=iso-8859-5
+// Needs work likely to contain errors
+//
+//Example mapping the Portugeuse charset
+//ISO_8859_1_E7 = KEY_SEMICOLON
+
+// 32 
+ASCII_20 = KEY_SPACE
+
+//numbers
+//?1234567890-?
+//?!"GBP$%<<>>*()_?
+ISO_8859_5_F1 = KEY_TILDE
+ISO_8859_5_A1 = KEY_TILDE, MODIFIERKEY_SHIFT
+ISO_8859_5_31 = KEY_1
+ISO_8859_5_21 = KEY_1, MODIFIERKEY_SHIFT
+ISO_8859_5_32 = KEY_2
+ISO_8859_5_22 = KEY_2, MODIFIERKEY_SHIFT
+ISO_8859_5_33 = KEY_3
+ISO_8859_5_23 = KEY_3, MODIFIERKEY_SHIFT
+ISO_8859_5_34 = KEY_4
+ISO_8859_5_24 = KEY_4, MODIFIERKEY_SHIFT
+ISO_8859_5_35 = KEY_5
+ISO_8859_5_25 = KEY_5, MODIFIERKEY_SHIFT
+ISO_8859_5_36 = KEY_6
+ISO_8859_5_26 = KEY_6, MODIFIERKEY_SHIFT
+ISO_8859_5_37 = KEY_7
+ISO_8859_5_27 = KEY_7, MODIFIERKEY_SHIFT
+ISO_8859_5_38 = KEY_8
+ISO_8859_5_2A = KEY_8, MODIFIERKEY_SHIFT
+ISO_8859_5_39 = KEY_9
+ISO_8859_5_28 = KEY_9, MODIFIERKEY_SHIFT
+ISO_8859_5_30 = KEY_0
+ISO_8859_5_29 = KEY_0, MODIFIERKEY_SHIFT
+ISO_8859_5_2D = KEY_MINUS
+ISO_8859_5_5F = KEY_MINUS, MODIFIERKEY_SHIFT
+ISO_8859_5_CA = KEY_EQUALS
+ISO_8859_5_EA = KEY_EQUALS, MODIFIERKEY_SHIFT
+
+//letters - 1st row
+//????????????
+//????????????
+ISO_8859_5_CF = KEY_Q, MODIFIERKEY_SHIFT
+ISO_8859_5_EF = KEY_Q
+ISO_8859_5_C8 = KEY_W, MODIFIERKEY_SHIFT
+ISO_8859_5_E8 = KEY_W
+ISO_8859_5_B5 = KEY_E, MODIFIERKEY_SHIFT
+ISO_8859_5_D5 = KEY_E
+ISO_8859_5_C0 = KEY_R, MODIFIERKEY_SHIFT
+ISO_8859_5_E0 = KEY_R
+ISO_8859_5_C2 = KEY_Y, MODIFIERKEY_SHIFT
+ISO_8859_5_E2 = KEY_Y
+ISO_8859_5_CB = KEY_U, MODIFIERKEY_SHIFT
+ISO_8859_5_EB = KEY_U
+ISO_8859_5_C3 = KEY_I, MODIFIERKEY_SHIFT
+ISO_8859_5_E3 = KEY_I
+ISO_8859_5_B8 = KEY_O, MODIFIERKEY_SHIFT
+ISO_8859_5_D8 = KEY_O
+ISO_8859_5_BE = KEY_P, MODIFIERKEY_SHIFT
+ISO_8859_5_DE = KEY_P
+ISO_8859_5_CE = KEY_LEFT_BRACE, MODIFIERKEY_SHIFT
+ISO_8859_5_EE = KEY_LEFT_BRACE
+ISO_8859_5_C9 = KEY_RIGHT_BRACE, MODIFIERKEY_SHIFT
+ISO_8859_5_E9 = KEY_RIGHT_BRACE
+
+//2nd row
+//???????????No
+//???????????~
+ISO_8859_5_B0 = KEY_A, MODIFIERKEY_SHIFT
+ISO_8859_5_D0 = KEY_A
+ISO_8859_5_C1 = KEY_S, MODIFIERKEY_SHIFT
+ISO_8859_5_E1 = KEY_S
+ISO_8859_5_B4 = KEY_D, MODIFIERKEY_SHIFT
+ISO_8859_5_D4 = KEY_D
+ISO_8859_5_B3 = KEY_G, MODIFIERKEY_SHIFT
+ISO_8859_5_D3 = KEY_G
+ISO_8859_5_B9 = KEY_J, MODIFIERKEY_SHIFT
+ISO_8859_5_D9 = KEY_J
+ISO_8859_5_BA = KEY_K, MODIFIERKEY_SHIFT
+ISO_8859_5_DA = KEY_K
+ISO_8859_5_BB = KEY_L, MODIFIERKEY_SHIFT
+ISO_8859_5_DB = KEY_L
+ISO_8859_5_CC = KEY_COLON, MODIFIERKEY_SHIFT
+ISO_8859_5_EC = KEY_COLON
+ISO_8859_5_B6 = KEY_QUOTE, MODIFIERKEY_SHIFT
+ISO_8859_5_D6 = KEY_QUOTE
+ISO_8859_5_F0 = KEY_BACKSLASH, MODIFIERKEY_SHIFT
+ISO_8859_5_7E = KEY_BACKSLASH
+
+//3rd row
+//???????,./
+//???????;:?
+ISO_8859_5_B7 = KEY_Z, MODIFIERKEY_SHIFT
+ISO_8859_5_D7 = KEY_Z
+ISO_8859_5_C5 = KEY_X, MODIFIERKEY_SHIFT
+ISO_8859_5_E5 = KEY_X
+ISO_8859_5_C6 = KEY_C, MODIFIERKEY_SHIFT
+ISO_8859_5_E6 = KEY_C
+ISO_8859_5_B2 = KEY_V, MODIFIERKEY_SHIFT
+ISO_8859_5_D2 = KEY_V
+ISO_8859_5_B1 = KEY_B, MODIFIERKEY_SHIFT
+ISO_8859_5_D1 = KEY_B
+ISO_8859_5_BD = KEY_N, MODIFIERKEY_SHIFT
+ISO_8859_5_DD = KEY_N
+ISO_8859_5_BC = KEY_M, MODIFIERKEY_SHIFT
+ISO_8859_5_DC = KEY_M
+ISO_8859_5_2C = KEY_COMMA, MODIFIERKEY_SHIFT
+ISO_8859_5_3B = KEY_COMMA
+ISO_8859_5_2E = KEY_PERIOD, MODIFIERKEY_SHIFT
+ISO_8859_5_3A = KEY_PERIOD
+ISO_8859_5_2F = KEY_SLASH, MODIFIERKEY_SHIFT
+ISO_8859_5_3F = KEY_SLASH
diff --git a/language/ru.properties b/language/ru.properties.orig
similarity index 100%
rename from language/ru.properties
rename to language/ru.properties.orig
diff --git a/main.go b/main.go
index fff2ed1..13a145e 100644
--- a/main.go
+++ b/main.go
@@ -25,7 +25,7 @@ func fatal(v interface{}) {
 }
 
 func main() {
-	flag.StringVar(&language, "l", "de", "language (available: be, br, ca, ch, de, dk, es, fi, fr, gb, hr, it, no, pt, ru, si, sv, tr, us)")
+	flag.StringVar(&language, "l", "de", "language (available: be, br, ca, ch, de, dk, es, fi, fr, gb, hr, it, no, pt, si, sv, tr, us)")
 	flag.StringVar(&inFile, "f", "", "input file")
 	flag.StringVar(&outFile, "o", "inject.bin", "output file (use - for stdout)")
 	flag.Parse()
@@ -45,7 +45,10 @@ func main() {
 			fatal(err)
 		}
 	}
-	e := encoder.NewEncoder(out, "de")
+	e, err := encoder.NewEncoder(out, language)
+	if err != nil {
+		fatal(err)
+	}
 	err = e.Encode(in)
 	if err != nil {
 		fatal(err)
diff --git a/pkg/encoder/encoder.go b/pkg/encoder/encoder.go
index 24d93f6..cd1ef47 100644
--- a/pkg/encoder/encoder.go
+++ b/pkg/encoder/encoder.go
@@ -21,11 +21,9 @@ type Encoder struct {
 	repeat        bool
 }
 
-func NewEncoder(w io.Writer, language string) *Encoder {
-	if language == "" {
-		language = "de"
-	}
-	return &Encoder{w, language, 0, false, 0, false}
+func NewEncoder(w io.Writer, language string) (*Encoder, error) {
+	err := lang.Exists(language)
+	return &Encoder{w, language, 0, false, 0, false}, err
 }
 
 func (e *Encoder) Encode(r io.Reader) (err error) {
diff --git a/pkg/encoder/encoder_test.go b/pkg/encoder/encoder_test.go
index ec8f668..69fd301 100644
--- a/pkg/encoder/encoder_test.go
+++ b/pkg/encoder/encoder_test.go
@@ -15,7 +15,11 @@ REM Hello World
 `)
 		out = new(bytes.Buffer)
 	)
-	err := NewEncoder(out, "de").Encode(in)
+	e, err := NewEncoder(out, "de")
+	if err != nil {
+		t.Error(err)
+	}
+	err = e.Encode(in)
 	if err != nil {
 		t.Error(err)
 	}
@@ -34,7 +38,11 @@ STRING Hello World
 			0x12, 0x0, 0x2c, 0x0, 0x1a, 0x2, 0x12, 0x0,
 			0x15, 0x0, 0xf, 0x0, 0x7, 0x0}
 	)
-	err := NewEncoder(out, "de").Encode(in)
+	e, err := NewEncoder(out, "de")
+	if err != nil {
+		t.Error(err)
+	}
+	err = e.Encode(in)
 	if err != nil {
 		t.Error(err)
 	}
@@ -68,7 +76,11 @@ STRING Hello World
 			0xf, 0x0, 0x12, 0x0, 0x2c, 0x0, 0x1a, 0x2,
 			0x12, 0x0, 0x15, 0x0, 0xf, 0x0, 0x7, 0x0}
 	)
-	err := NewEncoder(out, "de").Encode(in)
+	e, err := NewEncoder(out, "de")
+	if err != nil {
+		t.Error(err)
+	}
+	err = e.Encode(in)
 	if err != nil {
 		t.Error(err)
 	}
@@ -77,6 +89,18 @@ STRING Hello World
 	}
 }
 
+func TestError(t *testing.T) {
+	out := new(bytes.Buffer)
+	_, err := NewEncoder(out, "")
+	if err == nil {
+		t.Error("language '' should not be supported")
+	}
+	_, err = NewEncoder(out, "fizzbuzz")
+	if err == nil {
+		t.Error("language 'fizzbuzz' should not be supported")
+	}
+}
+
 func BenchmarkExample(b *testing.B) {
 	var in = bytes.NewBufferString(`
 REM Type Hello World into Windows notepad. Target: Windows 95 and beyond. Author: Darren
@@ -88,7 +112,10 @@ ENTER
 DELAY 1000
 STRING Hello World
 `)
-	e := NewEncoder(ioutil.Discard, "de")
+	e, err := NewEncoder(ioutil.Discard, "de")
+	if err != nil {
+		b.Error(err)
+	}
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
 		e.Encode(in)
diff --git a/pkg/lang/lang.go b/pkg/lang/lang.go
index d88fa88..66d565b 100644
--- a/pkg/lang/lang.go
+++ b/pkg/lang/lang.go
@@ -2,6 +2,8 @@
 
 package lang
 
+import "errors"
+
 var L = make(map[string]Lang)
 
 type Lang map[string]Key
@@ -10,3 +12,10 @@ type Key struct {
 	Key byte
 	Mod byte
 }
+
+func Exists(l string) error {
+	if _, ok := L[l]; !ok {
+		return errors.New("language '" + l + "' is not supported")
+	}
+	return nil
+}
diff --git a/pkg/lang/ru.go b/pkg/lang/ru.go
deleted file mode 100644
index d82078d..0000000
--- a/pkg/lang/ru.go
+++ /dev/null
@@ -1,11 +0,0 @@
-package lang
-
-import "git.giftfish.de/ston1th/duckycode/pkg/keys"
-
-func init() {
-	L["ru"] = ru
-}
-
-var ru = Lang{
-	"Binary": Key{keys.K["file"], keys.K["language/ru.properties"]},
-}