diff --git a/hotp/hotp.go b/hotp/hotp.go
index 951cd0b..d190928 100644
--- a/hotp/hotp.go
+++ b/hotp/hotp.go
@@ -77,6 +77,10 @@ func GenerateCodeCustom(secret string, counter uint64, opts ValidateOpts) (passc
 		secret = secret + strings.Repeat("=", 8-n)
 	}
 
+	// As noted in issue #24 Google has started producing base32 in lower case,
+	// but the StdEncoding (and the RFC), expect a dictionary of only upper case letters.
+	secret = strings.ToUpper(secret)
+
 	secretBytes, err := base32.StdEncoding.DecodeString(secret)
 	if err != nil {
 		return "", otp.ErrValidateSecretInvalidBase32
diff --git a/hotp/hotp_test.go b/hotp/hotp_test.go
index 9640144..bc885a5 100644
--- a/hotp/hotp_test.go
+++ b/hotp/hotp_test.go
@@ -120,6 +120,16 @@ func TestValidatePadding(t *testing.T) {
 	require.Equal(t, true, valid, "Valid should be true.")
 }
 
+func TestValidateLowerCaseSecret(t *testing.T) {
+	valid, err := ValidateCustom("831097", 0, "jbswy3dpehpk3px",
+		ValidateOpts{
+			Digits:    otp.DigitsSix,
+			Algorithm: otp.AlgorithmSHA1,
+		})
+	require.NoError(t, err, "Expected no error.")
+	require.Equal(t, true, valid, "Valid should be true.")
+}
+
 func TestGenerate(t *testing.T) {
 	k, err := Generate(GenerateOpts{
 		Issuer:      "SnakeOil",
diff --git a/totp/totp_test.go b/totp/totp_test.go
index 75c114e..ce58883 100644
--- a/totp/totp_test.go
+++ b/totp/totp_test.go
@@ -144,3 +144,17 @@ func TestGenerate(t *testing.T) {
 	require.NoError(t, err, "Secret size is valid when length not divisable by 5.")
 	require.NotContains(t, k.Secret(), "=", "Secret has no escaped characters.")
 }
+
+func TestGoogleLowerCaseSecret(t *testing.T) {
+	w, err := otp.NewKeyFromURL(`otpauth://totp/Google%3Afoo%40example.com?secret=qlt6vmy6svfx4bt4rpmisaiyol6hihca&issuer=Google`)
+	require.NoError(t, err)
+	sec := w.Secret()
+	require.Equal(t, "qlt6vmy6svfx4bt4rpmisaiyol6hihca", sec)
+
+	n := time.Now().UTC()
+	code, err := GenerateCode(w.Secret(), n)
+	require.NoError(t, err)
+
+	valid := Validate(code, w.Secret())
+	require.True(t, valid)
+}