diff --git a/go.mod b/go.mod
index 5867ed5..632891a 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module github.com/iand/microdata
 
 go 1.16
+
+require golang.org/x/net v0.0.0-20200904194848-62affa334b73
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..76714ba
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,9 @@
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20200904194848-62affa334b73 h1:MXfv8rhZWmFeqX3GNZRsd6vOLoaCHjYEX3qkRo3YBUA=
+golang.org/x/net v0.0.0-20200904194848-62affa334b73/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/microdata_test.go b/microdata_test.go
index 01bdc97..63b167e 100644
--- a/microdata_test.go
+++ b/microdata_test.go
@@ -594,6 +594,6 @@ func TestSkipSelfReferencingItemref(t *testing.T) {
 	expected.AddItem(item)
 
 	if !reflect.DeepEqual(expected, actual) {
-		t.Errorf("Expecting %s but got %s", expected, actual)
+		t.Errorf("Expecting %v but got %v", expected, actual)
 	}
 }