Add alias APPLE make var of APPLE_BUILD
diff --git a/library/Makefile b/library/Makefile
index 60e9cbc..9affde4 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -21,6 +21,8 @@
 # if were running on Windows build for Windows
 ifdef WINDOWS
 WINDOWS_BUILD=1
+else ifdef APPLE
+APPLE_BUILD=1
 endif
 
 # To compile as a shared library: