diff --git a/indra/libhacd/hacdMicroAllocator.cpp b/indra/libhacd/hacdMicroAllocator.cpp
index c49789842..47562f6a4 100644
--- a/indra/libhacd/hacdMicroAllocator.cpp
+++ b/indra/libhacd/hacdMicroAllocator.cpp
@@ -50,8 +50,9 @@
 #include <pthread.h>
 #endif
 
-
+#if defined(_WIN32)
 #pragma warning(disable:4100)
+#endif
 
 namespace HACD
 {