README.md  | 9 +++++++++
 decoder.go | 6 ++++--

diff --git a/README.md b/README.md
index 152737d8e06b3583ad958c95dfe9b6964a1d0d0b..28a67f8ef504ef24367cb04b9c48fc9cdb4f0187 100644
--- a/README.md
+++ b/README.md
@@ -108,6 +108,15 @@     ch2 := pcm[(i*channels)+(channels-1)]
 }
 ```
 
+Note regarding Forward Error Correction (FEC):
+> When a packet is considered "lost", `DecodeFEC` and `DecodeFECFloat32` methods
+> can be called on the next packet in order to try and recover some of the lost
+> data. The PCM needs to be exactly the duration of audio that is missing.
+> `LastPacketDuration()` can be used on the decoder to get the length of the
+> last packet.
+> Note also that in order to use this feature the encoder needs to be configured
+> with `SetInBandFEC(true)` and `SetPacketLossPerc(x)` options.
+
 ### Streams (and files)
 
 To decode a .opus file (or .ogg with Opus data), or to decode a "Opus stream"
diff --git a/decoder.go b/decoder.go
index fe888ac1e323cabb5da65575f5725115662fc5d7..a3760ce2421a0fb333ec8fc01e75df66142bef7e 100644
--- a/decoder.go
+++ b/decoder.go
@@ -113,7 +113,8 @@ 	return n, nil
 }
 
 // DecodeFEC encoded Opus data into the supplied buffer with forward error
-// correction. The supplied buffer will be entirely filled.
+// correction. It is to be used on the packet directly following the lost one.
+// The supplied buffer needs to be exactly the duration of audio that is missing
 func (dec *Decoder) DecodeFEC(data []byte, pcm []int16) error {
 	if dec.p == nil {
 		return errDecUninitialized
@@ -139,7 +140,8 @@ 	return nil
 }
 
 // DecodeFECFloat32 encoded Opus data into the supplied buffer with forward error
-// correction. The supplied buffer will be entirely filled.
+// correction. It is to be used on the packet directly following the lost one.
+// The supplied buffer needs to be exactly the duration of audio that is missing
 func (dec *Decoder) DecodeFECFloat32(data []byte, pcm []float32) error {
 	if dec.p == nil {
 		return errDecUninitialized