diff --git a/hurd/thread-self.c b/hurd/thread-self.c
index af013503bf..494a127aa5 100644
--- a/hurd/thread-self.c
+++ b/hurd/thread-self.c
@@ -16,6 +16,7 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <hurd.h>
 #include <hurd/signal.h>
 
 thread_t