diff --git a/src/isaac64.c b/src/isaac64.c
index 76cb769fc..e95eb8131 100644
--- a/src/isaac64.c
+++ b/src/isaac64.c
@@ -12,7 +12,6 @@
 #include "config.h"
 
 #ifdef USE_ISAAC64
-#include <math.h>
 #include <string.h>
 #include "isaac64.h"