diff --git a/utils/wrappers/packing_test.go b/utils/wrappers/packing_test.go
index 8678f46..6937d27 100644
--- a/utils/wrappers/packing_test.go
+++ b/utils/wrappers/packing_test.go
@@ -43,6 +43,22 @@ func TestPackerCheckSpace(t *testing.T) {
 	}
 }
 
+func TestPackerExpand(t *testing.T) {
+	p := Packer{Bytes: []byte{0x01}, Offset: 2}
+	p.Expand(1)
+	if !p.Errored() {
+		t.Fatal("packer.Expand didn't notice packer had out of bounds offset")
+	}
+
+	p = Packer{Bytes: []byte{0x01, 0x02, 0x03}, Offset: 0}
+	p.Expand(1)
+	if p.Errored() {
+		t.Fatalf("packer.Expand unexpectedly had error %s", p.Err)
+	} else if len(p.Bytes) != 3 {
+		t.Fatalf("packer.Expand modified byte array, when it didn't need to")
+	}
+}
+
 func TestPackerPackByte(t *testing.T) {
 	p := Packer{MaxSize: 1}