Bug: https://bugs.gentoo.org/600894

--- a/insaneodyssey/io.cpp
+++ b/insaneodyssey/io.cpp
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <cmath>
 
 #include <SDL/SDL.h>
 
@@ -894,7 +895,7 @@
 	else
 	{	
 	   if ( jumping )
-	      yspeed = -jumpheight - abs(xspeed)/4;
+	      yspeed = -jumpheight - std::abs(xspeed)/4;
 	}
 
     	short TempX = (x + width/2) / TILESIZE;