diff --git a/ean/encoder.go b/ean/encoder.go
index d7aacc7..5363bb9 100644
--- a/ean/encoder.go
+++ b/ean/encoder.go
@@ -78,14 +78,14 @@ var encoderTable map[rune]encodedNumber = map[rune]encodedNumber{
 }
 
 func runeToInt(r rune) int {
-	if r >= '0' || r <= '9' {
+	if r >= '0' && r <= '9' {
 		return int(r - '0')
 	}
 	return -1
 }
 
 func intToRune(i int) rune {
-	if i >= 0 || i <= 9 {
+	if i >= 0 && i <= 9 {
 		return rune(i + '0')
 	}
 	return 'F'
diff --git a/ean/encoder_test.go b/ean/encoder_test.go
index e2d1e2c..43bcdd3 100644
--- a/ean/encoder_test.go
+++ b/ean/encoder_test.go
@@ -5,19 +5,63 @@ import (
 	"testing"
 )
 
-func Test_EncodeEAN13(t *testing.T) {
-	testResult := "10100010110100111011001100100110111101001110101010110011011011001000010101110010011101000100101"
-	testCode := "5901234123457"
+func testHelper(t *testing.T, testCode, testResult, kind string, checkMetadata bool) {
 	code, err := Encode(testCode)
 	if err != nil {
 		t.Error(err)
 	}
-	if code.Metadata().Dimensions != 1 || code.Content() != testCode || code.Metadata().CodeKind != "EAN 13" {
+	if checkMetadata && (code.Metadata().Dimensions != 1 || code.Content() != testCode || code.Metadata().CodeKind != kind) {
 		t.Error("Metadata missmatch")
 	}
+	if len(testResult) != code.Bounds().Max.X {
+		t.Fail()
+	}
 	for i, r := range testResult {
 		if (code.At(i, 0) == color.Black) != (r == '1') {
 			t.Fail()
 		}
 	}
 }
+
+func Test_EncodeEAN(t *testing.T) {
+	testHelper(t, "5901234123457", "10100010110100111011001100100110111101001110101010110011011011001000010101110010011101000100101", "EAN 13", true)
+	testHelper(t, "55123457", "1010110001011000100110010010011010101000010101110010011101000100101", "EAN 8", true)
+	testHelper(t, "5512345", "1010110001011000100110010010011010101000010101110010011101000100101", "EAN 8", false)
+	_, err := Encode("55123458") //<-- Invalid checksum
+	if err == nil {
+		t.Error("Invalid checksum not detected")
+	}
+	_, err = Encode("invalid")
+	if err == nil {
+		t.Error("\"invalid\" should not be encodable")
+	}
+	_, err = Encode("invalid")
+	if err == nil {
+		t.Error("\"invalid\" should not be encodable")
+	}
+	bits := encodeEAN13("invalid error")
+	if bits != nil {
+		t.Error("\"invalid error\" should not be encodable")
+	}
+}
+
+func Test_RuneToIntIntToRune(t *testing.T) {
+	if intToRune(0) != '0' {
+		t.Errorf("failed intToRune(0) returned %d", string(intToRune(0)))
+	}
+	if intToRune(9) != '9' {
+		t.Errorf("failed intToRune(9) returned %d", intToRune(9))
+	}
+	if intToRune(10) != 'F' {
+		t.Errorf("failed intToRune(10) returned %d", intToRune(10))
+	}
+	if runeToInt('0') != 0 {
+		t.Error("failed runeToInt('0') returned %d", runeToInt(0))
+	}
+	if runeToInt('9') != 9 {
+		t.Error("failed runeToInt('9') returned %d", runeToInt(9))
+	}
+	if runeToInt('F') != -1 {
+		t.Error("failed runeToInt('F') returned %d", runeToInt('F'))
+	}
+}