diff --git a/command/agent/config_test.go b/command/agent/config_test.go
index 40c9eca27..2c8571fa8 100644
--- a/command/agent/config_test.go
+++ b/command/agent/config_test.go
@@ -2,6 +2,7 @@ package agent
 
 import (
 	"io/ioutil"
+	"net"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -541,3 +542,14 @@ func TestResources_ParseReserved(t *testing.T) {
 
 	}
 }
+
+func TestIsMissingPort(t *testing.T) {
+	_, _, err := net.SplitHostPort("localhost")
+	if missing := isMissingPort(err); !missing {
+		t.Errorf("expected missing port error, but got %v", err)
+	}
+	_, _, err = net.SplitHostPort("localhost:9000")
+	if missing := isMissingPort(err); missing {
+		t.Errorf("expected no error, but got %v", err)
+	}
+}