diff --git a/indra/llcommon/llapp.h b/indra/llcommon/llapp.h
index 963ea38249..27a52cdd99 100644
--- a/indra/llcommon/llapp.h
+++ b/indra/llcommon/llapp.h
@@ -43,7 +43,9 @@ template <typename Type> class LLAtomic32;
 typedef LLAtomic32<U32> LLAtomicU32;
 class LLErrorThread;
 class LLLiveFile;
+#if LL_LINUX
 typedef struct siginfo siginfo_t;
+#endif
 
 typedef void (*LLAppErrorHandler)();
 typedef void (*LLAppChildCallback)(int pid, bool exited, int status);