diff --git a/src/block_cache.cpp b/src/block_cache.cpp
index 58ae89f..c8aec41 100644
--- a/src/block_cache.cpp
+++ b/src/block_cache.cpp
@@ -31,7 +31,7 @@ namespace p2pool {
 
 struct BlockCache::Impl : public nocopy_nomove
 {
-#if defined(__linux__) || defined(__unix__) || defined(_POSIX_VERSION)
+#if defined(__linux__) || defined(__unix__) || defined(_POSIX_VERSION) || defined(__MACH__)
 
 	Impl()
 	{