diff --git a/roaring/roaring.go b/roaring/roaring.go
index 1dcf5e7cb..7b1d24666 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -35,8 +35,8 @@ const (
 
 	// cookie is the first four bytes in a roaring bitmap file,
 	// formed by joining magicNumber and storageVersion
-	cookieNoRuns = magicNumberNoRuns<<16 + storageVersion
-	cookie       = magicNumber<<16 + storageVersion
+	cookieNoRuns = magicNumberNoRuns + storageVersion<<16
+	cookie       = magicNumber + storageVersion<<16
 
 	// headerBaseSize is the size of the cookie and key count at the beginning of a file.
 	// Headers in files with runs also include runFlagBitset, of length (numContainers+7)/8.
@@ -630,15 +630,20 @@ func (b *Bitmap) UnmarshalBinary(data []byte) error {
 		return errors.New("data too small")
 	}
 
-	// Verify the first sizeof(cookie)=4 bytes are a valid cookie.
-	v := binary.LittleEndian.Uint32(data[0:4])
+	// Verify the first two bytes are a valid magicNumber, and second two bytes match current storageVersion.
+	fileMagic := uint32(binary.LittleEndian.Uint16(data[0:2]))
+	fileVersion := uint32(binary.LittleEndian.Uint16(data[2:4]))
 	containsRuns := false
-	if v == cookieNoRuns {
+	if fileMagic == magicNumberNoRuns {
 		// noop
-	} else if v == cookie {
+	} else if fileMagic == magicNumber {
 		containsRuns = true
 	} else {
-		return errors.New("invalid roaring file")
+		return fmt.Errorf("invalid roaring file, magic number %v is incorrect", fileMagic)
+	}
+
+	if fileVersion != storageVersion {
+		return fmt.Errorf("wrong roaring version, file is v%d, server requires v%d", fileVersion, storageVersion)
 	}
 
 	// Read key count in bytes sizeof(cookie):(sizeof(cookie)+sizeof(uint32)).
diff --git a/roaring/roaring_internal_test.go b/roaring/roaring_internal_test.go
index 3ee835d8a..7d35779ce 100644
--- a/roaring/roaring_internal_test.go
+++ b/roaring/roaring_internal_test.go
@@ -1341,8 +1341,14 @@ func TestWriteReadArray(t *testing.T) {
 	ba := &Bitmap{keys: []uint64{0}, containers: []*container{ca}}
 	ba2 := &Bitmap{}
 	var buf bytes.Buffer
-	ba.WriteTo(&buf)
-	ba2.UnmarshalBinary(buf.Bytes())
+	_, err := ba.WriteTo(&buf)
+	if err != nil {
+		t.Fatalf("error writing: %v", err)
+	}
+	err = ba2.UnmarshalBinary(buf.Bytes())
+	if err != nil {
+		t.Fatalf("error unmarshaling: %v", err)
+	}
 	if !reflect.DeepEqual(ba2.containers[0].array, ca.array) {
 		t.Fatalf("array test expected %x, but got %x", ca.array, ba2.containers[0].array)
 	}
@@ -1357,8 +1363,14 @@ func TestWriteReadBitmap(t *testing.T) {
 	bb := &Bitmap{keys: []uint64{0}, containers: []*container{cb}}
 	bb2 := &Bitmap{}
 	var buf bytes.Buffer
-	bb.WriteTo(&buf)
-	bb2.UnmarshalBinary(buf.Bytes())
+	_, err := bb.WriteTo(&buf)
+	if err != nil {
+		t.Fatalf("error writing: %v", err)
+	}
+	err = bb2.UnmarshalBinary(buf.Bytes())
+	if err != nil {
+		t.Fatalf("error unmarshaling: %v", err)
+	}
 	if !reflect.DeepEqual(bb2.containers[0].bitmap, cb.bitmap) {
 		t.Fatalf("bitmap test expected %x, but got %x", cb.bitmap, bb2.containers[0].bitmap)
 	}
@@ -1369,8 +1381,14 @@ func TestWriteReadRun(t *testing.T) {
 	br := &Bitmap{keys: []uint64{0}, containers: []*container{cr}}
 	br2 := &Bitmap{}
 	var buf bytes.Buffer
-	br.WriteTo(&buf)
-	br2.UnmarshalBinary(buf.Bytes())
+	_, err := br.WriteTo(&buf)
+	if err != nil {
+		t.Fatalf("error writing: %v", err)
+	}
+	err = br2.UnmarshalBinary(buf.Bytes())
+	if err != nil {
+		t.Fatalf("error unmarshaling: %v", err)
+	}
 	if !reflect.DeepEqual(br2.containers[0].runs, cr.runs) {
 		t.Fatalf("run test expected %x, but got %x", cr.runs, br2.containers[0].runs)
 	}