3 files changed, 49 insertions, 8 deletions
diff --git a/README.md b/README.md
index 930072b..5f181a8 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,11 @@ Hub](https://hub.docker.com/r/mpolden/echoip), which can be downloaded with:
 
 `docker pull mpolden/echoip`
 
+## [GeoIP](https://www.maxmind.com/en/geoip2-databases)/[GeoLite](https://dev.maxmind.com/geoip/geolite2-free-geolocation-data?) Database (MaxMind)
+To utilise MaxMind [GeoIP](https://www.maxmind.com/en/geoip2-databases)/[GeoLite](https://dev.maxmind.com/geoip/geolite2-free-geolocation-data?) database to enhance the information provided to end users, you can download the relevant **binary** databases (`.mmdb` format) directly from MaxMind using the above links.
+
+**Please Note**: This has only been tested using the free, GeoLite database.
+
 ### Usage
 
 ```
diff --git a/cmd/echoip/main.go b/cmd/echoip/main.go
index 737a4f4..f3d4c94 100644
--- a/cmd/echoip/main.go
+++ b/cmd/echoip/main.go
@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"log"
+	"strings"
 
 	"os"
 
@@ -14,14 +15,7 @@ import (
 type multiValueFlag []string
 
 func (f *multiValueFlag) String() string {
-	vs := ""
-	for i, v := range *f {
-		vs += v
-		if i < len(*f)-1 {
-			vs += ", "
-		}
-	}
-	return vs
+	return strings.Join([]string(*f), ", ")
 }
 
 func (f *multiValueFlag) Set(v string) error {
diff --git a/cmd/echoip/main_test.go b/cmd/echoip/main_test.go
new file mode 100644
index 0000000..045a82a
--- /dev/null
+++ b/cmd/echoip/main_test.go
@@ -0,0 +1,42 @@
+package main
+
+import "testing"
+
+func TestMultiValueFlagString(t *testing.T) {
+	var xmvf = []struct {
+		values multiValueFlag
+		expect string
+	}{
+		{
+			values: multiValueFlag{
+				"test",
+				"with multiples",
+				"flags",
+			},
+			expect: `test, with multiples, flags`,
+		},
+		{
+			values: multiValueFlag{
+				"test",
+			},
+			expect: `test`,
+		},
+		{
+			values: multiValueFlag{
+				"",
+			},
+			expect: ``,
+		},
+		{
+			values: nil,
+			expect: ``,
+		},
+	}
+
+	for _, mvf := range xmvf {
+		got := mvf.values.String()
+		if got != mvf.expect {
+			t.Errorf("\nFor: %#v\nExpected: %v\nGot: %v", mvf.values, mvf.expect, got)
+		}
+	}
+}