diff --git a/gen/elem.go b/gen/elem.go
index 565e694..2a339ed 100644
--- a/gen/elem.go
+++ b/gen/elem.go
@@ -91,10 +91,11 @@ const (
 	Int32
 	Int64
 	Bool
-	Intf  // interface{}
-	Time  // time.Time
-	Ext   // extension
-	Error // error
+	Intf     // interface{}
+	Time     // time.Time
+	Ext      // extension
+	Error    // error
+	Duration // time.Duration
 
 	IDENT // IDENT means an unrecognized identifier
 )
@@ -126,6 +127,7 @@ var primitives = map[string]Primitive{
 	"time.Time":      Time,
 	"msgp.Extension": Ext,
 	"error":          Error,
+	"time.Duration":  Duration,
 }
 
 // types built into the library
@@ -757,11 +759,14 @@ func (s *BaseElem) FromBase() string {
 // BaseName returns the string form of the
 // base type (e.g. Float64, Ident, etc)
 func (s *BaseElem) BaseName() string {
-	// time is a special case;
+	// time and duration are special cases;
 	// we strip the package prefix
 	if s.Value == Time {
 		return "Time"
 	}
+	if s.Value == Duration {
+		return "Duration"
+	}
 	return s.Value.String()
 }
 
@@ -841,7 +846,8 @@ func (s *BaseElem) ZeroExpr() string {
 		Int8,
 		Int16,
 		Int32,
-		Int64:
+		Int64,
+		Duration:
 		return "0"
 	case Bool:
 		return "false"
@@ -933,6 +939,8 @@ func (k Primitive) String() string {
 		return "Intf"
 	case Time:
 		return "time.Time"
+	case Duration:
+		return "time.Duration"
 	case Ext:
 		return "Extension"
 	case IDENT:
diff --git a/msgp/read_bytes.go b/msgp/read_bytes.go
index bc1467c..1d6a308 100644
--- a/msgp/read_bytes.go
+++ b/msgp/read_bytes.go
@@ -387,6 +387,16 @@ func ReadBoolBytes(b []byte) (bool, []byte, error) {
 	}
 }
 
+// ReadDurationBytes tries to read a time.Duration
+// from 'b' and return the value and the remaining bytes.
+// Possible errors:
+// - ErrShortBytes (too few bytes)
+// - TypeError (not a int)
+func ReadDurationBytes(b []byte) (d time.Duration, o []byte, err error) {
+	i, o, err := ReadInt64Bytes(b)
+	return time.Duration(i), o, err
+}
+
 // ReadInt64Bytes tries to read an int64
 // from 'b' and return the value and the remaining bytes.
 // Possible errors:
diff --git a/msgp/size.go b/msgp/size.go
index ce2f8b1..e3a613b 100644
--- a/msgp/size.go
+++ b/msgp/size.go
@@ -25,9 +25,10 @@ const (
 	Complex64Size  = 10
 	Complex128Size = 18
 
-	TimeSize = 15
-	BoolSize = 1
-	NilSize  = 1
+	DurationSize = Int64Size
+	TimeSize     = 15
+	BoolSize     = 1
+	NilSize      = 1
 
 	MapHeaderSize   = 5
 	ArrayHeaderSize = 5
diff --git a/msgp/write_bytes.go b/msgp/write_bytes.go
index 24bc20c..b96715c 100644
--- a/msgp/write_bytes.go
+++ b/msgp/write_bytes.go
@@ -75,6 +75,11 @@ func AppendFloat32(b []byte, f float32) []byte {
 	return o
 }
 
+// AppendDuration appends a time.Duration to the slice
+func AppendDuration(b []byte, d time.Duration) []byte {
+	return AppendInt64(b, int64(d))
+}
+
 // AppendInt64 appends an int64 to the slice
 func AppendInt64(b []byte, i int64) []byte {
 	if i >= 0 {