diff --git a/mongoose.c b/mongoose.c
index 3cb1be74290ac173a41d5f73bf3d989ca452d1c0..8459a43e6da8b45abe1d36c8b15c84669caefe2d 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -1336,7 +1336,7 @@ static pid_t spawn_process(struct mg_connection *conn, const char *prog,
   DEBUG_TRACE(("Running [%s]", cmdline));
   if (CreateProcessA(NULL, cmdline, NULL, NULL, TRUE,
         CREATE_NEW_PROCESS_GROUP, envblk, NULL, &si, &pi) == 0) {
-    cry(conn, "%s: CreateProcess(%s): %d",
+    cry(conn, "%s: CreateProcess(%s): %ld",
         __func__, cmdline, ERRNO);
     pi.hProcess = (pid_t) -1;
   }
@@ -5195,7 +5195,7 @@ struct mg_context *mg_start(const struct mg_callbacks *callbacks,
   // Start worker threads
   for (i = 0; i < atoi(ctx->config[NUM_THREADS]); i++) {
     if (mg_start_thread(worker_thread, ctx) != 0) {
-      cry(fc(ctx), "Cannot start worker thread: %d", ERRNO);
+      cry(fc(ctx), "Cannot start worker thread: %ld", ERRNO);
     } else {
       ctx->num_threads++;
     }