diff --git a/Python/thread.c b/Python/thread.c
index ad7dd5c..2d04256 100644
--- a/Python/thread.c
+++ b/Python/thread.c
@@ -49,6 +49,12 @@
 #include <unistd.h>
 #endif
 
+#ifdef __sgi
+#ifndef HAVE_PTHREAD_H /* XXX Need to check in configure.in */
+#undef _POSIX_THREADS
+#endif
+#endif
+
 #include "thread.h"
 
 #ifdef __ksr__