diff --git a/decimal_magpack_test.go b/decimal_magpack_test.go
index 41d9dd2..bc865a4 100644
--- a/decimal_magpack_test.go
+++ b/decimal_magpack_test.go
@@ -7,7 +7,7 @@ import (
 func TestMsgPack(t *testing.T) {
 	for _, x := range testTable {
 		s := x.short
-		 // limit to 31 digits
+		// limit to 31 digits
 		if len(s) > 31 {
 			s = s[:31]
 			if s[30] == '.' {
@@ -17,15 +17,15 @@ func TestMsgPack(t *testing.T) {
 
 		// Prepare Test Decimal Data
 		amount, err := NewFromString(s)
-		if err != nil{
+		if err != nil {
 			t.Error(err)
 		}
 		s = amount.String()
 
 		// MarshalMsg
 		var b []byte
-	 	out, err := amount.MarshalMsg(b)
-		if err != nil{
+		out, err := amount.MarshalMsg(b)
+		if err != nil {
 			t.Errorf("error marshalMsg %s: %v", s, err)
 		}
 
@@ -44,12 +44,12 @@ func TestMsgPack(t *testing.T) {
 		// UnmarshalMsg
 		var unmarshalAmount Decimal
 		_, err = unmarshalAmount.UnmarshalMsg(out)
-		if err != nil{
+		if err != nil {
 			t.Errorf("error unmarshalMsg %s: %v", s, err)
-		}else if !unmarshalAmount.Equal(amount) {
-				t.Errorf("expected %s, got %s (%s, %d)",
-					amount.String(), unmarshalAmount.String(),
-					unmarshalAmount.value.String(), unmarshalAmount.exp)
+		} else if !unmarshalAmount.Equal(amount) {
+			t.Errorf("expected %s, got %s (%s, %d)",
+				amount.String(), unmarshalAmount.String(),
+				unmarshalAmount.value.String(), unmarshalAmount.exp)
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/decimal_msgpack.go b/decimal_msgpack.go
index 2e205f4..55d22d2 100644
--- a/decimal_msgpack.go
+++ b/decimal_msgpack.go
@@ -26,7 +26,7 @@ func (d Decimal) MarshalMsg(b []byte) ([]byte, error) {
 		str = str[:sz]
 	}
 
-	o, n := ensure(b, 1+sz)
+	o, n := ensure(o, 1+sz)
 	o[n] = byte(0xa0 | sz)
 	n++
 
@@ -54,7 +54,7 @@ func (d *Decimal) UnmarshalMsg(b []byte) ([]byte, error) {
 
 // Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message
 func (d Decimal) Msgsize() int {
-	return 31
+	return 32
 }
 
 // Require ensures that cap(old)-len(old) >= extra.