diff --git a/cmd/rqlited/main.go b/cmd/rqlited/main.go
index bd8de5be..1863a4fd 100644
--- a/cmd/rqlited/main.go
+++ b/cmd/rqlited/main.go
@@ -21,7 +21,6 @@ import (
 	"os/signal"
 	"path/filepath"
 	"runtime/pprof"
-	"strings"
 
 	"github.com/otoolep/rqlite/auth"
 	sql "github.com/otoolep/rqlite/db"
@@ -206,10 +205,7 @@ func join(joinAddr string, skipVerify bool, raftAddr string) error {
 	}
 
 	// Check for protocol scheme, and insert default if necessary.
-	fullAddr := fmt.Sprintf("%s/join", joinAddr)
-	if !strings.HasPrefix(joinAddr, "http://") && !strings.HasPrefix(joinAddr, "https://") {
-		fullAddr = fmt.Sprintf("http://%s", joinAddr)
-	}
+	fullAddr := httpd.NormalizeAddr(fmt.Sprintf("%s/join", joinAddr))
 
 	// Enable skipVerify as requested.
 	tr := &http.Transport{
diff --git a/http/service.go b/http/service.go
index e6618308..74bfe150 100644
--- a/http/service.go
+++ b/http/service.go
@@ -591,3 +591,12 @@ func prettyEnabled(e bool) string {
 	}
 	return "disabled"
 }
+
+// NormalizeAddr ensures that the given URL has a HTTP protocol prefix.
+// If none is supplied, it prefixes the URL with "http://".
+func NormalizeAddr(addr string) string {
+	if !strings.HasPrefix(addr, "http://") && !strings.HasPrefix(addr, "https://") {
+		return fmt.Sprintf("http://%s", addr)
+	}
+	return addr
+}
diff --git a/http/service_test.go b/http/service_test.go
index 0d22df34..adb3d762 100644
--- a/http/service_test.go
+++ b/http/service_test.go
@@ -9,6 +9,44 @@ import (
 	"github.com/otoolep/rqlite/store"
 )
 
+func Test_NormalizeAddr(t *testing.T) {
+	tests := []struct {
+		orig string
+		norm string
+	}{
+		{
+			orig: "http://localhost:4001",
+			norm: "http://localhost:4001",
+		},
+		{
+			orig: "https://localhost:4001",
+			norm: "https://localhost:4001",
+		},
+		{
+			orig: "https://localhost:4001/foo",
+			norm: "https://localhost:4001/foo",
+		},
+		{
+			orig: "localhost:4001",
+			norm: "http://localhost:4001",
+		},
+		{
+			orig: "localhost",
+			norm: "http://localhost",
+		},
+		{
+			orig: ":4001",
+			norm: "http://:4001",
+		},
+	}
+
+	for _, tt := range tests {
+		if NormalizeAddr(tt.orig) != tt.norm {
+			t.Fatalf("%s not normalized correctly, got: %s", tt.orig, tt.norm)
+		}
+	}
+}
+
 func Test_NewService(t *testing.T) {
 	m := &MockStore{}
 	s := New("127.0.0.1:0", m, nil)