diff --git a/lib/matrix/svd.c b/lib/matrix/svd.c
index 536eb6a..bd3bfbc 100644
--- a/lib/matrix/svd.c
+++ b/lib/matrix/svd.c
@@ -29,7 +29,7 @@
  *  converge at the 'kth' singular value.
  * 
  */
-#ifdef MACOS
+#ifdef __APPLE__
   #include <sys/malloc.h> /* for array allocation */
 #else
   #include <malloc.h>