1 files changed, 4 insertions, 0 deletions

diff --git a/src/thread.h b/src/thread.h
index cb2133d72d4..19baafbf8a1 100644
--- a/src/thread.h
+++ b/src/thread.h
@@ -25,6 +25,10 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include <sys/socket.h>
 #endif
 
+#ifdef MSDOS
+#include <signal.h>             /* sigset_t */
+#endif
+
 #include "sysselect.h"          /* FIXME */
 #include "systime.h"            /* FIXME */
 #include "systhread.h"