diff --git a/CHANGELOG.md b/CHANGELOG.md
index 628a15aeb2..41cb224721 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## HEAD
 
+* Fix `tls.Unmarshal` decoding a `Uint24` field from the start of the buffer instead of the field's offset by @robstradling
 * Switch Ed25519 import from deprecated `golang.org/x/crypto/ed25519` to stdlib `crypto/ed25519` by @JasonPowr
 * Added `--emit_proxy_headers` flag to ctfe by @mhutchinson
 
diff --git a/tls/tls.go b/tls/tls.go
index a48c998f48..dd7356ab29 100644
--- a/tls/tls.go
+++ b/tls/tls.go
@@ -336,7 +336,7 @@ func parseField(v reflect.Value, data []byte, initOffset int, info *fieldInfo) (
 		if len(rest) < 3 {
 			return offset, syntaxError{info.fieldName(), "truncated uint24"}
 		}
-		v.SetUint(uint64(data[0])<<16 | uint64(data[1])<<8 | uint64(data[2]))
+		v.SetUint(uint64(rest[0])<<16 | uint64(rest[1])<<8 | uint64(rest[2]))
 		offset += 3
 		return offset, nil
 	case uint32Type:
diff --git a/tls/tls_test.go b/tls/tls_test.go
index fd20874421..9215e10c63 100644
--- a/tls/tls_test.go
+++ b/tls/tls_test.go
@@ -68,6 +68,11 @@ type testSliceOfSlices struct {
 	Inners []testInnerType `tls:"minlen:0,maxlen:65535"`
 }
 
+type testUint24AtOffset struct {
+	Prefix uint16
+	Val    Uint24
+}
+
 func TestMarshalUnmarshalRoundTrip(t *testing.T) {
 	thing := testStruct{Data: []byte{0x01, 0x02, 0x03}, IntVal: 42, Other: [4]byte{1, 2, 3, 4}, Enum: 17}
 	data, err := Marshal(thing)
@@ -187,6 +192,7 @@ func TestUnmarshalMarshalWithParamsRoundTrip(t *testing.T) {
 		// Note that maxval is just used to give enum size; it's not policed
 		{"20", "maxval:18", newEnum(32)},
 		{"020a0b", "minlen:1,maxlen:5", &[]byte{0xa, 0xb}},
+		{"0a0b010203", "", &testUint24AtOffset{Prefix: 0x0a0b, Val: 0x010203}},
 		{"020a0b0101010203040011", "", &testStruct{Data: []byte{0xa, 0xb}, IntVal: 0x101, Other: [4]byte{1, 2, 3, 4}, Enum: 17}},
 		{"000102", "", &testVariant{Which: 0, Val16: newUint16(0x0102)}},
 		{"0101020304", "", &testVariant{Which: 1, Val32: newUint32(0x01020304)}},