diff --git a/libfwupdplugin/fu-i2c-device.c b/libfwupdplugin/fu-i2c-device.c
index cca4d6633..852123919 100644
--- a/libfwupdplugin/fu-i2c-device.c
+++ b/libfwupdplugin/fu-i2c-device.c
@@ -114,8 +114,7 @@ fu_i2c_device_probe(FuDevice *device, GError **error)
 	FuI2cDevicePrivate *priv = GET_PRIVATE(self);
 	GUdevDevice *udev_device = fu_udev_device_get_dev(FU_UDEV_DEVICE(device));
 	const gchar *tmp;
-	g_autoptr(GMatchInfo) info = NULL;
-	g_autoptr(GRegex) regex = NULL;
+	g_autofree gchar *devname = NULL;
 #endif
 
 	/* set physical ID */
@@ -130,13 +129,13 @@ fu_i2c_device_probe(FuDevice *device, GError **error)
 		return FALSE;
 
 	/* get bus number out of sysfs path */
-	regex = g_regex_new("/i2c-([0-9]+)/", 0, 0, error);
-	if (regex == NULL)
-		return FALSE;
-	tmp = g_udev_device_get_sysfs_path(udev_device);
-	if (!g_regex_match_full(regex, tmp, -1, 0, 0, &info, error))
-		return FALSE;
-	priv->bus_number = g_ascii_strtoll(g_match_info_fetch(info, 1), NULL, 10);
+	devname = g_path_get_basename(fu_udev_device_get_sysfs_path(FU_UDEV_DEVICE(device)));
+	if (g_str_has_prefix(devname, "i2c-")) {
+		guint64 tmp64 = 0;
+		if (!fu_strtoull(devname + 4, &tmp64, 0, G_MAXUINT, error))
+			return FALSE;
+		priv->bus_number = tmp64;
+	}
 #endif
 
 	/* success */