diff --git a/Python/thread_solaris.h b/Python/thread_solaris.h
index 199d7d0..6a9c59e 100644
--- a/Python/thread_solaris.h
+++ b/Python/thread_solaris.h
@@ -26,6 +26,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include </usr/include/thread.h>
+#indef _POSIX_THREADS
 
 
 /*