diff --git a/src/fp.c b/src/fp.c
index 9593e51..3e275c5 100644
--- a/src/fp.c
+++ b/src/fp.c
@@ -18,6 +18,7 @@ static char *id = "$Id: fp.c,v 1.3 1999/05/31 23:35:29 sybalsky Exp $ Copyright
 /*									*/
 /************************************************************************/
 #include <stdio.h>
+#include <math.h>
 #include "lispemul.h"
 #include "lspglob.h"
 #include "adr68k.h"