diff --git a/Sources/OpenAISwift/OpenAISwift.swift b/Sources/OpenAISwift/OpenAISwift.swift
index dd4e27c..e07083a 100644
--- a/Sources/OpenAISwift/OpenAISwift.swift
+++ b/Sources/OpenAISwift/OpenAISwift.swift
@@ -7,6 +7,7 @@ import FoundationXML
 public enum OpenAIError: Error {
     case genericError(error: Error)
     case decodingError(error: Error)
+    case badResponse(code: Int, response: String?)
 }
 
 public class OpenAISwift {
@@ -170,8 +171,20 @@ extension OpenAISwift {
     private func makeRequest(request: URLRequest, completionHandler: @escaping (Result<Data, Error>) -> Void) {
         let session = config.session
         let task = session.dataTask(with: request) { (data, response, error) in
+
             if let error = error {
                 completionHandler(.failure(error))
+            } else if let response = response as? HTTPURLResponse,
+                      !(200...299).contains(response.statusCode) {
+                //Responses outside the 2xx range don't necessarily throw errors, but we should treat them as errors
+                //E.g. a rejected api key will generate a 401 and a helpful message, but no error
+                let code = response.statusCode
+                var responseString:String?
+                if let data {
+                    responseString = String(data:data,encoding: .utf8)
+                }
+
+                completionHandler(.failure(OpenAIError.badResponse(code: code, response: responseString)))
             } else if let data = data {
                 completionHandler(.success(data))
             }