diff --git a/archive/tar/reader.go b/archive/tar/reader.go
index fdc8ae3..adf3212 100644
--- a/archive/tar/reader.go
+++ b/archive/tar/reader.go
@@ -608,12 +608,12 @@ func (tr *Reader) readHeader() *Header {
 	header := tr.hdrBuff[:]
 	copy(header, zeroBlock)
 
-	if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil {
+	if n, err := io.ReadFull(tr.r, header); err != nil {
+		tr.err = err
 		// because it could read some of the block, but reach EOF first
 		if tr.err == io.EOF && tr.RawAccounting {
-			if _, err := tr.rawBytes.Write(header); err != nil {
+			if _, err := tr.rawBytes.Write(header[:n]); err != nil {
 				tr.err = err
-				return nil
 			}
 		}
 		return nil // io.EOF is okay here
@@ -626,11 +626,12 @@ func (tr *Reader) readHeader() *Header {
 
 	// Two blocks of zero bytes marks the end of the archive.
 	if bytes.Equal(header, zeroBlock[0:blockSize]) {
-		if _, tr.err = io.ReadFull(tr.r, header); tr.err != nil {
+		if n, err := io.ReadFull(tr.r, header); err != nil {
+			tr.err = err
 			// because it could read some of the block, but reach EOF first
 			if tr.err == io.EOF && tr.RawAccounting {
-				if _, tr.err = tr.rawBytes.Write(header); tr.err != nil {
-					return nil
+				if _, err := tr.rawBytes.Write(header[:n]); err != nil {
+					tr.err = err
 				}
 			}
 			return nil // io.EOF is okay here
diff --git a/tar/asm/assemble_test.go b/tar/asm/assemble_test.go
index c0c7f17..afdce9d 100644
--- a/tar/asm/assemble_test.go
+++ b/tar/asm/assemble_test.go
@@ -139,6 +139,8 @@ var testCases = []struct {
 	{"./testdata/longlink.tar.gz", "d9f6babe107b7247953dff6b5b5ae31a3a880add", 20480},
 	{"./testdata/fatlonglink.tar.gz", "8537f03f89aeef537382f8b0bb065d93e03b0be8", 26234880},
 	{"./testdata/iso-8859.tar.gz", "ddafa51cb03c74ec117ab366ee2240d13bba1ec3", 10240},
+	{"./testdata/extranils.tar.gz", "e187b4b3e739deaccc257342f4940f34403dc588", 10648},
+	{"./testdata/notenoughnils.tar.gz", "72f93f41efd95290baa5c174c234f5d4c22ce601", 512},
 }
 
 func TestTarStream(t *testing.T) {
diff --git a/tar/asm/testdata/extranils.tar.gz b/tar/asm/testdata/extranils.tar.gz
new file mode 100644
index 0000000..70caf6e
Binary files /dev/null and b/tar/asm/testdata/extranils.tar.gz differ
diff --git a/tar/asm/testdata/notenoughnils.tar.gz b/tar/asm/testdata/notenoughnils.tar.gz
new file mode 100644
index 0000000..146bb00
Binary files /dev/null and b/tar/asm/testdata/notenoughnils.tar.gz differ