diff --git a/go.mod b/go.mod
index b359a22..7306c19 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,3 @@
 module github.com/go-piv/piv-go
 
-go 1.13
+go 1.16
diff --git a/piv/pcsc_unix.go b/piv/pcsc_unix.go
index 55d6318..66d590e 100644
--- a/piv/pcsc_unix.go
+++ b/piv/pcsc_unix.go
@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//go:build darwin || linux || freebsd
 // +build darwin linux freebsd
 
 package piv