diff --git a/dll/auth.cpp b/dll/auth.cpp
index 0a1d9888..83c178d0 100644
--- a/dll/auth.cpp
+++ b/dll/auth.cpp
@@ -310,7 +310,7 @@ void Auth_Manager::Callback(Common_Message *msg)
 
     if (msg->has_auth_ticket()) {
         if (msg->auth_ticket().type() == Auth_Ticket::CANCEL) {
-            PRINT_DEBUG("TICKET CANCEL %llu\n", msg->source_id());
+            PRINT_DEBUG("TICKET CANCEL " "%" PRIu64 "\n", msg->source_id());
             uint32 number = msg->auth_ticket().number();
             auto t = std::begin(inbound);
             while (t != std::end(inbound)) {
diff --git a/dll/auth.h b/dll/auth.h
index ca3d29cf..fb3289f2 100644
--- a/dll/auth.h
+++ b/dll/auth.h
@@ -515,7 +515,7 @@ struct Auth_Data {
             "AUTH::Auth_Data::SER:\n"
             "  HasGC: %u\n"
             "  user steam_id: " "%" PRIu64 "\n"
-            "  number: %llu\n",
+            "  number: " "%" PRIu64 "\n",
 
             (int)HasGC,
             steam_id,