diff --git a/passes/cmds/bugpoint.cc b/passes/cmds/bugpoint.cc
index 11f6de35b..101d82bd6 100644
--- a/passes/cmds/bugpoint.cc
+++ b/passes/cmds/bugpoint.cc
@@ -21,6 +21,7 @@
 #include "backends/rtlil/rtlil_backend.h"
 
 #if defined(_WIN32)
+#  include <csignal>
 #  define WIFEXITED(x) 1
 #  define WIFSIGNALED(x) 0
 #  define WIFSTOPPED(x) 0