diff --git a/src/kmer.gleam b/src/kmer.gleam
index 7d0e682..bdc0b5d 100644
--- a/src/kmer.gleam
+++ b/src/kmer.gleam
@@ -2,6 +2,7 @@ import birl.{type Time}
 import gleam/bit_array
 import gleam/list.{reverse}
 import gleam/result.{try}
+import gleam/uri.{type Uri}
 import ieee_float.{
   type IEEEFloat, finite, from_bytes_16_be, from_bytes_32_be, from_bytes_64_be,
   multiply, power, round,
@@ -16,6 +17,12 @@ pub type DecodedValue {
   Array(List(DecodedValue))
   Map(List(#(DecodedValue, DecodedValue)))
   DateTime(Time)
+  EncodedCBOR(value: BitArray)
+  URI(Uri)
+  BigNum(bytes: BitArray, negative: Bool)
+  Base64(value: String)
+  Base64URL(value: String)
+  Mime(value: String)
   Null
   Undefined
 }
@@ -29,6 +36,9 @@ pub type DecodeResult =
 pub opaque type DecodeError {
   // Malformed sequence found
   Malformed
+
+  // Not implemented
+  NotImplemented
 }
 
 pub fn decode(bits: BitArray) -> DecodeResult {
@@ -113,6 +123,17 @@ fn decode_tag(bits: BitArray) -> DecodeResult {
   case tag {
     0 -> decode_datestring(rest) |> map_decoded(DateTime)
     1 -> decode_unixtime(rest) |> map_decoded(DateTime)
+    2 -> decode_bigint(rest, False)
+    3 -> decode_bigint(rest, True)
+    // not willing to implement bigfloats tbh
+    4 -> Error(NotImplemented)
+    // todo
+    21 -> Error(NotImplemented)
+    // todo
+    22 -> Error(NotImplemented)
+    // todo
+    23 -> Error(NotImplemented)
+    24 -> decode_bytestring(rest) |> map_decoded(EncodedCBOR)
     // CBOR magic number (no-op for us)
     55_799 -> decode(rest)
     _ -> Error(Malformed)
@@ -158,6 +179,17 @@ fn decode_unixtime(bits: BitArray) -> DecoderResult(Time) {
   }
 }
 
+fn decode_bigint(bits: BitArray, negative: Bool) -> DecodeResult {
+  // Must be bytes
+  case bits {
+    <<2:3, rest:bits>> -> {
+      use #(bytes, remainder) <- try(decode_bytestring(rest))
+      Ok(#(BigNum(bytes, negative), remainder))
+    }
+    _ -> Error(Malformed)
+  }
+}
+
 fn decode_float(bits: BitArray) -> DecoderResult(IEEEFloat) {
   case bits {
     <<25:5, float16:bytes-size(2), rest:bits>> ->