diff --git a/src/UpdateChecker/UpdateChecker.cpp b/src/UpdateChecker/UpdateChecker.cpp
index abd3cc4..dd44d5b 100644
--- a/src/UpdateChecker/UpdateChecker.cpp
+++ b/src/UpdateChecker/UpdateChecker.cpp
@@ -37,6 +37,17 @@ UpdateChecker::~UpdateChecker() {
     curl_global_cleanup();
 }
 
+inline
+std::size_t
+writeCallback(char* data, std::size_t size, std::size_t nmemb, void* user_data) {
+    if(!data || !user_data) return std::size_t{};
+
+    auto* s = static_cast<Containers::String*>(user_data);
+    (*s) = (*s) + Containers::StringView{data, size * nmemb};
+
+    return size * nmemb;
+}
+
 UpdateChecker::Result
 UpdateChecker::check() {
     auto curl = curl_easy_init();
@@ -48,16 +59,11 @@ UpdateChecker::check() {
 
     Containers::String response_body{Containers::AllocatedInit, ""};
     Containers::String error_buffer{ValueInit, CURL_ERROR_SIZE};
-    static auto write_data = [](char* ptr, std::size_t size, std::size_t nmemb, Containers::String* buf){
-        if(!ptr || !buf) return std::size_t{};
-        (*buf) = Utility::format("{}{}", *buf, Containers::StringView{ptr, size * nmemb});
-        return size * nmemb;
-    };
 
     curl_easy_setopt(curl, CURLOPT_URL, "https://williamjcm.ovh/mbst/version");
     curl_easy_setopt(curl, CURLOPT_HTTPGET, 1L);
     curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 1L);
-    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeCallback);
     curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_body);
     curl_easy_setopt(curl, CURLOPT_ERRORBUFFER, error_buffer.data());
     curl_easy_setopt(curl, CURLOPT_TCP_KEEPALIVE, 0L);