diff --git a/include/mathlib.h b/include/mathlib.h
index c92e0d9..89ca7cc 100644
--- a/include/mathlib.h
+++ b/include/mathlib.h
@@ -57,7 +57,11 @@ struct mplane_s;
 extern vec3_t vec3_origin;
 extern int nanmask;
 
-#define	IS_NAN(x) (((*(int *)&x)&nanmask)==nanmask)
+#define	IS_NAN(x) ({ \
+	int tmp;			\
+	memcpy(&tmp, &x, sizeof(int));	\
+	((tmp & nanmask) == nanmask);	\
+})
 
 #define DotProduct(x,y) (x[0]*y[0]+x[1]*y[1]+x[2]*y[2])
 #define VectorSubtract(a,b,c) {c[0]=a[0]-b[0];c[1]=a[1]-b[1];c[2]=a[2]-b[2];}