diff --git a/unix/tcl.m4 b/unix/tcl.m4
index 9f15d52..7fad3a8 100644
--- a/unix/tcl.m4
+++ b/unix/tcl.m4
@@ -2366,7 +2366,7 @@ AC_DEFUN([SC_TIME_HANDLER], [
 #include <stdlib.h>]],
 	[[extern long timezone;
 	    timezone += 1;
-	    exit (0);]])],
+	    return 0;]])],
 	    [tcl_cv_timezone_long=yes], [tcl_cv_timezone_long=no])])
     if test $tcl_cv_timezone_long = yes ; then
 	AC_DEFINE(HAVE_TIMEZONE_VAR, 1, [Should we use the global timezone variable?])
@@ -2379,7 +2379,7 @@ AC_DEFUN([SC_TIME_HANDLER], [
 #include <stdlib.h>]],
 	    [[extern time_t timezone;
 		timezone += 1;
-		exit (0);]])],
+		return 0;]])],
 		[tcl_cv_timezone_time=yes], [tcl_cv_timezone_time=no])])
 	if test $tcl_cv_timezone_time = yes ; then
 	    AC_DEFINE(HAVE_TIMEZONE_VAR, 1, [Should we use the global timezone variable?])