1 files changed, 1 insertions, 1 deletions
diff --git a/math.c b/math.c
index e3a78f74e3..7e073d7fe7 100644
--- a/math.c
+++ b/math.c
@@ -10,6 +10,7 @@
 **********************************************************************/
 
 #include "ruby/ruby.h"
+#include "internal.h"
 #include <math.h>
 #include <errno.h>
 
@@ -18,7 +19,6 @@
 VALUE rb_mMath;
 VALUE rb_eMathDomainError;
 
-extern VALUE rb_to_float(VALUE val);
 #define Need_Float(x) do {if (TYPE(x) != T_FLOAT) {(x) = rb_to_float(x);}} while(0)
 #define Need_Float2(x,y) do {\
     Need_Float(x);\