diff --git a/src/input/plugins/TidalTagScanner.cxx b/src/input/plugins/TidalTagScanner.cxx
index c7584f4ce..da4e6abae 100644
--- a/src/input/plugins/TidalTagScanner.cxx
+++ b/src/input/plugins/TidalTagScanner.cxx
@@ -23,6 +23,8 @@
 #include "tag/Builder.hxx"
 #include "tag/Tag.hxx"
 
+#include <cassert>
+
 using Wrapper = Yajl::CallbacksWrapper<TidalTagScanner::ResponseParser>;
 static constexpr yajl_callbacks parse_callbacks = {
 	nullptr,