Index: src/platform/posix/thread.m
==================================================================
--- src/platform/posix/thread.m
+++ src/platform/posix/thread.m
@@ -162,11 +162,12 @@
 
 		ctx->function = function;
 		ctx->object = object;
 		ctx->name = name;
 
-		error = pthread_create(thread, &POSIXAttr, functionWrapper,
+		error = pthread_create(thread,
+		    (POSIXAttrAvailable ? &POSIXAttr : NULL), functionWrapper,
 		    ctx);
 	} @finally {
 		if (POSIXAttrAvailable)
 			pthread_attr_destroy(&POSIXAttr);
 	}