diff '--color=auto' -ruN a/src/pmars.c b/src/pmars.c
--- a/src/pmars.c	2024-11-12 20:36:28.142766807 +0100
+++ b/src/pmars.c	2024-11-12 20:39:48.096710063 +0100
@@ -72,7 +72,7 @@
 #ifdef PSPACE
 void    pspace_init(void);
 #endif
-#if defined(unix) || defined(__MSDOS__) || defined(VMS)
+#if defined(unix) || defined(__MSDOS__) || defined(VMS) || defined(__MACH__)
 void    sighandler(int dummy);
 #endif
 #if defined(CURSESGRAPHX)
@@ -87,7 +87,7 @@
 #ifdef PSPACE
 void    pspace_init();
 #endif
-#if defined(unix) || defined(__MSDOS__)
+#if defined(unix) || defined(__MSDOS__) || defined(__MACH__)
 void    sighandler();
 #endif
 #if defined(CURSESGRAPHX)
@@ -224,7 +224,7 @@
 }
 
 /* called when ctrl-c is pressed; prepares for debugger entry */
-#if defined(unix) || defined(__MSDOS__) || defined (__OS2__)
+#if defined(unix) || defined(__MSDOS__) || defined (__OS2__) || defined(__MACH__)
 void
 #ifdef __OS2__
         _cdecl
@@ -290,7 +290,7 @@
   int     argc;
   char  **argv;
 {
-#if defined(unix) && !defined(DJGPP)
+#if (defined(unix) && !defined(DJGPP)) || defined(__MACH__)
 #ifdef SIGINT
   signal(SIGINT, sighandler);
 #endif
diff '--color=auto' -ruN a/src/xwindisp.c b/src/xwindisp.c
--- a/src/xwindisp.c	2024-11-12 20:36:28.143766827 +0100
+++ b/src/xwindisp.c	2024-11-12 20:37:39.708178145 +0100
@@ -61,6 +61,9 @@
 #define YELLOW                        14
 #define WHITE                         15
 
+/* defined in pmars.c */
+extern void sighandler(int dummy);
+
  /* X names of the colors we allocate */
 static char *xColorNames[MAXXCOLOR] = {
   "black", "blue3", "green3", "cyan3",