diff --git a/rtpconn/rtp_test.go b/rtpconn/rtp_test.go
new file mode 100644
index 0000000..3cf8099
--- /dev/null
+++ b/rtpconn/rtp_test.go
@@ -0,0 +1,48 @@
+package rtpconn
+
+import (
+	"testing"
+
+	"github.com/pion/rtp"
+)
+
+func TestVP8Keyframe(t *testing.T) {
+	ps := [][]byte{
+		{
+
+			0x80, 0xe0, 0x71, 0x3e, 0x5d, 0x6f, 0x3c, 0xc5,
+			0x75, 0xc, 0x80, 0x96, 0x90, 0x80, 0xb0, 0x4c,
+			0x90, 0x2, 0x0, 0x9d, 0x1, 0x2a, 0x10, 0x0, 0x10,
+			0x0, 0x39, 0x3, 0x0, 0x0, 0x1c, 0x22, 0x16, 0x16,
+			0x22, 0x66, 0x12, 0x20, 0x4, 0x90, 0x40, 0x4e,
+			0x9e, 0x8d, 0xe9, 0x40, 0xfe, 0xff, 0xab, 0x59,
+			0x72, 0x30, 0xd1, 0xaf, 0xe4, 0x6a, 0x11, 0x3,
+			0xfd, 0x15, 0xe9, 0x2, 0x2e, 0xdf, 0xd9, 0xd1,
+			0xb8, 0x0, 0x0,
+		},
+		{
+			0x80, 0x6f, 0x61, 0x8f, 0xd5, 0x36, 0xdc, 0x15,
+			0x1b, 0x4a, 0xb5, 0x29, 0x78, 0x9, 0xa1, 0x93,
+			0xa0, 0x5b, 0xd8, 0xf1, 0xde, 0x87, 0x23, 0x5a,
+			0xb9, 0x19, 0x97, 0xb7, 0xbd, 0xbf, 0xf7, 0x6e,
+			0xad, 0x82, 0xc4, 0x70, 0x1c, 0xc9, 0x3a, 0xb4,
+			0x1f, 0x13, 0x45, 0xb5, 0xf1, 0x0, 0xa5, 0xa5,
+			0xa9, 0xd0, 0xa5, 0xdf, 0x67, 0x88, 0x26, 0x30,
+			0x32,
+		},
+	}
+
+	var packet rtp.Packet
+
+	for i, p := range ps {
+		err := packet.Unmarshal(p)
+		if err != nil {
+			t.Errorf("Unmarshal(p%v): %v", i, err)
+		}
+
+		kf, kfKnown := isKeyframe("video/vp8", &packet)
+		if kf != (i == 0) || !kfKnown {
+			t.Errorf("isKeyframe(p%v): %v %v", i, kf, kfKnown)
+		}
+	}
+}
diff --git a/rtpconn/rtpreader.go b/rtpconn/rtpreader.go
index 4316602..47645ca 100644
--- a/rtpconn/rtpreader.go
+++ b/rtpconn/rtpreader.go
@@ -13,15 +13,26 @@ import (
 	"github.com/jech/galene/rtptime"
 )
 
-func isVP8Keyframe(packet *rtp.Packet) bool {
-	var vp8 codecs.VP8Packet
-	_, err := vp8.Unmarshal(packet.Payload)
-	if err != nil {
-		return false
-	}
+// isKeyframe determines if packet is the start of a keyframe.
+// It returns (true, true) if that is the case, (false, true) if that is
+// definitely not the case, and (false, false) if the information cannot
+// be determined.
+func isKeyframe(codec string, packet *rtp.Packet) (bool, bool) {
+	switch strings.ToLower(codec) {
+	case "video/vp8":
+		var vp8 codecs.VP8Packet
+		_, err := vp8.Unmarshal(packet.Payload)
+		if err != nil || len(vp8.Payload) < 1 {
+			return false, false
+		}
 
-	return vp8.S != 0 && vp8.PID == 0 &&
-		len(vp8.Payload) > 0 && (vp8.Payload[0]&0x1) == 0
+		if vp8.S != 0 && vp8.PID == 0 && (vp8.Payload[0]&0x1) == 0 {
+			return true, true
+		}
+		return false, true
+	default:
+		return false, false
+	}
 }
 
 func readLoop(conn *rtpUpConnection, track *rtpUpTrack) {
@@ -54,10 +65,7 @@ func readLoop(conn *rtpUpConnection, track *rtpUpTrack) {
 
 		track.jitter.Accumulate(packet.Timestamp)
 
-		kf := false
-		if isvideo && strings.ToLower(codec.MimeType) == "video/vp8" {
-			kf = isVP8Keyframe(&packet)
-		}
+		kf, _ := isKeyframe(codec.MimeType, &packet)
 
 		first, index := track.cache.Store(
 			packet.SequenceNumber, packet.Timestamp,
diff --git a/rtpconn/rtpwriter.go b/rtpconn/rtpwriter.go
index 888967d..ad01df1 100644
--- a/rtpconn/rtpwriter.go
+++ b/rtpconn/rtpwriter.go
@@ -343,13 +343,8 @@ func rtpWriterLoop(writer *rtpWriter, up *rtpUpConnection, track *rtpUpTrack) {
 			}
 
 			if kfNeeded > kfUnneeded {
-				kf := false
-				kfValid := false
-				switch strings.ToLower(codec.MimeType) {
-				case "video/vp8":
-					kf = isVP8Keyframe(&packet)
-					kfValid = true
-				}
+				kf, kfKnown :=
+					isKeyframe(codec.MimeType, &packet)
 				if kf {
 					kfNeeded = kfUnneeded
 				}
@@ -370,7 +365,7 @@ func rtpWriterLoop(writer *rtpWriter, up *rtpUpConnection, track *rtpUpTrack) {
 					up.sendPLI(track)
 				}
 
-				if !kfValid {
+				if !kfKnown {
 					// we cannot detect keyframes for
 					// this codec, reset our state
 					kfNeeded = kfUnneeded