diff --git a/include/openai/openai.hpp b/include/openai/openai.hpp
index 16a65c9..71f2967 100644
--- a/include/openai/openai.hpp
+++ b/include/openai/openai.hpp
@@ -218,6 +218,9 @@ inline Response Session::makeRequest(const std::string& contentType) {
 
     res_ = curl_easy_perform(curl_);
 
+    /* free the list of headers */
+    curl_slist_free_all(headers);
+
     bool is_error = false;
     std::string error_msg{};
     if(res_ != CURLE_OK) {
@@ -438,7 +441,7 @@ class OpenAI {
             }
             if (api_base_url.empty()) {
                 if(const char* env_p = std::getenv("OPENAI_API_BASE")) {
-                    base_url = std::string{env_p} + "/";
+                    base_url = std::string{env_p};
                 }
                 else {
                     base_url = "https://api.openai.com/v1/";
@@ -447,6 +450,9 @@ class OpenAI {
             else {
                 base_url = api_base_url;
             }
+            if (not base_url.empty() and base_url.back() != '/') {
+                base_url += '/';
+            }
             session_.setUrl(base_url);
             session_.setToken(token_, organization_);
             session_.setBeta(beta);