diff --git a/src/semigrp.h b/src/semigrp.h
index f2d5463a..327a7f14 100644
--- a/src/semigrp.h
+++ b/src/semigrp.h
@@ -23,6 +23,7 @@
 
 #include "compiled.h"  // GAP headers
 
+#include "libsemigroups/element-adapters.hpp"
 #include "libsemigroups/froidure-pin.hpp"
 
 #include "converter.h"