diff --git a/oauth.go b/oauth.go
index 13a847f..be2cf58 100755
--- a/oauth.go
+++ b/oauth.go
@@ -188,8 +188,8 @@ func getBaseUrlString(u *url.URL) string {
 		host = hostPort[0]
 	}
 	path := u.EscapedPath()
-	if path == "" {
-		path = "/"
+	if path == "" || path[0] != '/' {
+		path = "/" + path
 	}
 	return fmt.Sprintf("%v://%v%v", scheme, host, path)
 }
diff --git a/oauth_test.go b/oauth_test.go
index cce1098..f60d00e 100755
--- a/oauth_test.go
+++ b/oauth_test.go
@@ -253,6 +253,15 @@ func TestGetBaseUrlString_ShouldAddTrailingSlash(t *testing.T) {
 	}
 }
 
+func TestGetBaseUrlString_ShouldAddLeadingSlashToPath(t *testing.T) {
+	u, _ := url.Parse("https://api.mastercard.com")
+	u.Path = "test/service"
+	baseUrl := getBaseUrlString(u)
+	if "https://api.mastercard.com/test/service" != baseUrl {
+		t.Errorf("Something went wrong, got %v", baseUrl)
+	}
+}
+
 func TestGetBaseUrlString_ShouldUseLowercaseSchemesAndHosts(t *testing.T) {
 	u, _ := url.Parse("HTTPS://API.MASTERCARD.COM/TEST")
 	baseUrl := getBaseUrlString(u)