diff --git a/Android.mk b/Android.mk
index 173b983..11a693d 100644
--- a/Android.mk
+++ b/Android.mk
@@ -177,7 +177,7 @@
 endif
 
 # Library extension for host-side tests
-ifeq ($(HOSTOS),darwin)
+ifeq ($(HOST_OS),darwin)
 SHAREDLIB_EXT=dylib
 else
 SHAREDLIB_EXT=so