diff --git a/cbor/cbor.go b/cbor/cbor.go
index 35079dca..c9e109de 100644
--- a/cbor/cbor.go
+++ b/cbor/cbor.go
@@ -32,8 +32,9 @@ const (
 	CBOR_MAX_UINT_SIMPLE uint8 = 0x17
 
 	// Useful tag numbers
-	CborTagSet = 258
-	CborTagMap = 259
+	CborTagRational = 30
+	CborTagSet      = 258
+	CborTagMap      = 259
 )
 
 // Create an alias for RawMessage for convenience
diff --git a/cbor/value.go b/cbor/value.go
index 23330910..f5946218 100644
--- a/cbor/value.go
+++ b/cbor/value.go
@@ -60,6 +60,12 @@ func (v *Value) UnmarshalCBOR(data []byte) error {
 			return err
 		}
 		switch tmpTag.Number {
+		case CborTagRational:
+			var tmpRat []int64
+			if _, err := Decode(tmpTag.Content, &tmpRat); err != nil {
+				return err
+			}
+			v.value = big.NewRat(tmpRat[0], tmpRat[1])
 		case CborTagSet:
 			return v.processArray(tmpTag.Content)
 		case CborTagMap: