diff --git a/src/r_videoscale.cpp b/src/r_videoscale.cpp
index d602062ae..55205e7b7 100644
--- a/src/r_videoscale.cpp
+++ b/src/r_videoscale.cpp
@@ -21,6 +21,7 @@
 //--------------------------------------------------------------------------
 //
 
+#include <math.h>
 #include "c_dispatch.h"
 #include "c_cvars.h"