diff --git a/src/liblzma/Aurora.json b/src/liblzma/Aurora.json
index 4426c04..f60e5e8 100644
--- a/src/liblzma/Aurora.json
+++ b/src/liblzma/Aurora.json
@@ -30,7 +30,15 @@
                 "platforms": "win32"
             },
             "then": {
-                "defines": ["MYTHREAD_VISTA"]
+                "defines": ["MYTHREAD_WIN95"]
+            }
+        },
+        {
+            "filter": {
+                "platforms": "linux"
+            },
+            "then": {
+                "defines": ["MYTHREAD_POSIX"]
             }
         }
     ],