diff --git a/src/mergerfs_webui.cpp b/src/mergerfs_webui.cpp
index 1d1b0b99..892476a0 100644
--- a/src/mergerfs_webui.cpp
+++ b/src/mergerfs_webui.cpp
@@ -3,6 +3,7 @@
 #include "mergerfs_api.hpp"
 #include "fs_mounts.hpp"
 #include "fs_exists.hpp"
+#include "str.hpp"
 
 #include "httplib.h"
 #include "json.hpp"