diff --git a/match.go b/match.go
index 82cf804..f22e46e 100644
--- a/match.go
+++ b/match.go
@@ -52,7 +52,7 @@ func MatchFile(filepath string) (types.Type, error) {
 }
 
 // MatchReader is convenient wrapper to Match() any Reader
-func MatchReader(reader io.Reader) (types.Type, error) {
+func MatchReader(reader io.ReadSeeker) (types.Type, error) {
 	buffer := make([]byte, 8192) // 8K makes msooxml tests happy and allows for expanded custom file checks
 
 	_, err := reader.Read(buffer)
@@ -60,6 +60,8 @@ func MatchReader(reader io.Reader) (types.Type, error) {
 		return types.Unknown, err
 	}
 
+	reader.Seek(0, 0)
+
 	return Match(buffer)
 }
 
diff --git a/match_test.go b/match_test.go
index 946bb25..09b31e1 100644
--- a/match_test.go
+++ b/match_test.go
@@ -71,12 +71,12 @@ func TestMatchFile(t *testing.T) {
 
 func TestMatchReader(t *testing.T) {
 	cases := []struct {
-		buf io.Reader
+		buf io.ReadSeeker
 		ext string
 	}{
-		{bytes.NewBuffer([]byte{0xFF, 0xD8, 0xFF}), "jpg"},
-		{bytes.NewBuffer([]byte{0xFF, 0xD8, 0x00}), "unknown"},
-		{bytes.NewBuffer([]byte{0x89, 0x50, 0x4E, 0x47}), "png"},
+		{bytes.NewReader([]byte{0xFF, 0xD8, 0xFF}), "jpg"},
+		{bytes.NewReader([]byte{0xFF, 0xD8, 0x00}), "unknown"},
+		{bytes.NewReader([]byte{0x89, 0x50, 0x4E, 0x47}), "png"},
 	}
 
 	for _, test := range cases {