diff --git a/ynab/client.go b/ynab/client.go
index b4a845b..ee98166 100644
--- a/ynab/client.go
+++ b/ynab/client.go
@@ -19,7 +19,7 @@ const apiBaseURL = "https://api.ynab.com/v1/budgets/"
 // endpoints. It holds the login credentials, http client/transport,
 // rate limit information, and the login session timer.
 type Client struct {
-	BearerToken string
+	bearerToken string
 	BudgetID    string
 	httpClient  *http.Client
 	transport   *http.Transport
@@ -32,7 +32,7 @@ func (c *Client) get(endpoint string, out interface{}, query url.Values) error {
 	if err != nil {
 		return fmt.Errorf("failed to create new GET request: %v", err)
 	}
-	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.BearerToken))
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.bearerToken))
 
 	res, err := c.httpClient.Do(req)
 	if err != nil {
@@ -58,7 +58,7 @@ func (c *Client) post(endpoint string, out interface{}, body interface{}) error
 	if err != nil {
 		return fmt.Errorf("failed to create new POST request: %v", err)
 	}
-	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.BearerToken))
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.bearerToken))
 	req.Header.Add("Content-Type", "application/json")
 
 	res, err := c.httpClient.Do(req)
@@ -85,7 +85,7 @@ func (c *Client) put(endpoint string, out interface{}, body interface{}) error {
 	if err != nil {
 		return fmt.Errorf("failed to create new POST request: %v", err)
 	}
-	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.BearerToken))
+	req.Header.Add("Authorization", fmt.Sprintf("Bearer %s", c.bearerToken))
 	req.Header.Add("Content-Type", "application/json")
 
 	res, err := c.httpClient.Do(req)
@@ -140,7 +140,7 @@ func NewClient(budgetID, bearerToken string) (*Client, error) {
 	// Create a new client
 	c := &Client{
 		BudgetID:    budgetID,
-		BearerToken: bearerToken,
+		bearerToken: bearerToken,
 		httpClient:  client,
 		transport:   transport,
 		loc:         loc,