diff --git a/invopop/invopop.go b/invopop/invopop.go
index c303c26..3e370c4 100644
--- a/invopop/invopop.go
+++ b/invopop/invopop.go
@@ -3,6 +3,7 @@ package invopop
 
 import (
 	"context"
+	"net/http"
 
 	"github.com/go-resty/resty/v2"
 )
@@ -26,6 +27,11 @@ const (
 	clientKey      invopopClientKey = "invopop-client"
 )
 
+// HTTPClient returns the underlying HTTP client (useful for mocking).
+func (c *Client) HTTPClient() *http.Client {
+	return c.conn.GetClient()
+}
+
 // Utils provides access to the utils service.
 func (c *Client) Utils() *UtilsService {
 	return (*UtilsService)(c.svc)
diff --git a/invopop/invopop_test.go b/invopop/invopop_test.go
index ebf6351..60e26a2 100644
--- a/invopop/invopop_test.go
+++ b/invopop/invopop_test.go
@@ -47,3 +47,11 @@ func Test_put(t *testing.T) {
 		})
 	}
 }
+
+func TestHTTPClient(t *testing.T) {
+	hc := new(http.Client)
+	c := &Client{
+		conn: resty.NewWithClient(hc),
+	}
+	assert.Equal(t, hc, c.HTTPClient())
+}