diff --git a/jwt.go b/jwt.go
index 80381e3..f77d634 100644
--- a/jwt.go
+++ b/jwt.go
@@ -219,7 +219,7 @@ func (m *Middleware) GenerateToken() http.Handler {
 		}
 
 		// Generate claims for user
-		claims, err := m.claims(m.identityField)
+		claims, err := m.claims(b[m.identityField])
 		if err != nil {
 			return &jwtError{
 				status:  http.StatusInternalServerError,