diff --git a/gdb/coredep.c b/gdb/coredep.c
index 84808bd9424..e216eedcb1d 100644
--- a/gdb/coredep.c
+++ b/gdb/coredep.c
@@ -32,6 +32,9 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #include <sys/file.h>
 #include <sys/stat.h>
 #include <sys/user.h>
+#ifdef USG
+#include <sys/ptrace.h>
+#endif
 
 
 /* Extract the register values out of the core file and store