diff --git a/zstd/decodeheader.go b/zstd/decodeheader.go
index 1f5d41bf41..f6a240970d 100644
--- a/zstd/decodeheader.go
+++ b/zstd/decodeheader.go
@@ -152,7 +152,7 @@ func (h *Header) Decode(in []byte) error {
 		}
 		b, in = in[:size], in[size:]
 		h.HeaderSize += int(size)
-		switch size {
+		switch len(b) {
 		case 1:
 			h.DictionaryID = uint32(b[0])
 		case 2:
@@ -182,7 +182,7 @@ func (h *Header) Decode(in []byte) error {
 		}
 		b, in = in[:fcsSize], in[fcsSize:]
 		h.HeaderSize += int(fcsSize)
-		switch fcsSize {
+		switch len(b) {
 		case 1:
 			h.FrameContentSize = uint64(b[0])
 		case 2:
diff --git a/zstd/framedec.go b/zstd/framedec.go
index 6cb3b4e55f..65984bf07c 100644
--- a/zstd/framedec.go
+++ b/zstd/framedec.go
@@ -167,7 +167,7 @@ func (d *frameDec) reset(br byteBuffer) error {
 			return err
 		}
 		var id uint32
-		switch size {
+		switch len(b) {
 		case 1:
 			id = uint32(b[0])
 		case 2:
@@ -204,7 +204,7 @@ func (d *frameDec) reset(br byteBuffer) error {
 			println("Reading Frame content", err)
 			return err
 		}
-		switch fcsSize {
+		switch len(b) {
 		case 1:
 			d.FrameContentSize = uint64(b[0])
 		case 2: