diff --git a/ofac.c b/ofac.c
index cdd73c7c..3e28f31c 100644
--- a/ofac.c
+++ b/ofac.c
@@ -104,6 +104,7 @@
 #include "lin2ang.h"
 #include "tas.h"
 #include "synchronize.h"
+#include "definealias.h"
 /*----------------------- Server options creation -------------------------*/
   static int IFServerOption(SConnection *pCon, SicsInterp *pSics, void *pData,
                      int argc, char *argv[])