diff --git a/indra/llkdu/llimagej2ckdu.h b/indra/llkdu/llimagej2ckdu.h
index 4895abdfc7..d82189b5df 100644
--- a/indra/llkdu/llimagej2ckdu.h
+++ b/indra/llkdu/llimagej2ckdu.h
@@ -32,7 +32,9 @@
 //
 // KDU core header files
 //
+#ifndef LL_WINDOWS
 #define KDU_NO_THREADS
+#endif
 
 #include "kdu_elementary.h"
 #include "kdu_messaging.h"
diff --git a/indra/llkdu/llkdumem.h b/indra/llkdu/llkdumem.h
index 4d9a48e575..80fa695ee7 100644
--- a/indra/llkdu/llkdumem.h
+++ b/indra/llkdu/llkdumem.h
@@ -34,7 +34,9 @@
 //</FS:TS>
 
 // Support classes for reading and writing from memory buffers in KDU
+#ifndef LL_WINDOWS
 #define KDU_NO_THREADS
+#endif
 
 #define kdu_xxxx "kdu_image.h"
 #include "include_kdu_xxxx.h"