diff --git a/lib/webapi.js b/lib/webapi.js
index c9f2983..8880bf4 100644
--- a/lib/webapi.js
+++ b/lib/webapi.js
@@ -25,7 +25,9 @@ TradeOfferManager.prototype._apiCall = function(httpMethod, method, version, inp
 
 	input = input || {};
 
-	if (this.apiKey) {
+	// We shouldn't strictly need to check useAccessToken here because we wouldn't have an API key anyway, but some
+	// people insist on manually assigning their API key despite the docs telling you not to do that.
+	if (this.apiKey && !this.useAccessToken) {
 		input.key = this.apiKey;
 	} else {
 		input.access_token = this.accessToken;