--- faac-1.29.9.2.old/libfaac/stereo.c
+++ faac-1.29.9.2/libfaac/stereo.c
@@ -21,6 +21,9 @@
 #include "stereo.h"
 #include "huff2.h"
 
+#ifndef M_SQRT2
+#define M_SQRT2    1.41421356237309504880
+#endif
 
 static void stereo(CoderInfo *cl, CoderInfo *cr,
                    double *sl0, double *sr0, int *sfcnt,