--- a/src/builtins.cc
+++ b/src/builtins.cc
@@ -40,8 +40,9 @@
 #include "help.h"
 #include "pager.h"
 #include "mappers.h"
+#include "variables.h"
 #include "user-prefs.h"
-#include "variables.h"
+#include "missing-math.h"
 
 // NOTE: nargin == 1 means that the function takes no arguments (just
 // like C, the first argument is (or should be, anyway) the function

--- a/src/g-builtins.cc
+++ b/src/g-builtins.cc
@@ -73,6 +73,7 @@
 #include "f-svd.h"
 #include "f-syl.h"
 
+#include "sighandlers.h"
 #include "procstream.h"
 #include "error.h"
 #include "variables.h"
@@ -114,16 +115,6 @@
 // of symbolic link following.
 static int verbatim_pwd = 1;
 
-// Signal handler return type.
-#ifndef RETSIGTYPE
-#define RETSIGTYPE void
-#endif
-#ifndef BADSIG
-#define BADSIG (RETSIGTYPE (*)())-1
-#endif
-
-typedef RETSIGTYPE sig_handler (...);
-
 /*
  * Are all elements of a constant nonzero?
  */

--- a/src/octave.cc
+++ b/src/octave.cc
@@ -63,16 +63,6 @@
 #include "file-io.h"
 #include "sysdep.h"
 
-// Signal handler return type.
-#ifndef RETSIGTYPE
-#define RETSIGTYPE void
-#endif
-#if 0
-#ifndef BADSIG
-#define BADSIG (RETSIGTYPE (*)())-1
-#endif
-#endif
-
 #ifdef sun
 extern "C" { int on_exit (); }
 #define atexit on_exit

--- a/src/sighandlers.h
+++ b/src/sighandlers.h
@@ -24,6 +24,16 @@
 #if !defined (_sighandlers_h)
 #define _sighandlers_h 1
 
+// Signal handler return type.
+#ifndef RETSIGTYPE
+#define RETSIGTYPE void
+#endif
+#ifndef BADSIG
+#define BADSIG (RETSIGTYPE (*)(int))-1
+#endif
+
+typedef RETSIGTYPE sig_handler (int);
+
 // Nonzero means we have already printed a message for this series of
 // SIGPIPES.  We assume that the writer will eventually give up.
 extern int pipe_handler_error_count;
@@ -31,8 +41,6 @@
 // Nonzero means we can be interrupted.
 extern int can_interrupt;
 
-typedef RETSIGTYPE sig_handler (...);
-
 extern void install_signal_handlers (void);
 
 #endif