--- at-3.1.13.orig/configure.ac
+++ at-3.1.13/configure.ac
@@ -17,8 +17,9 @@ AC_SUBST(VERSION)
 AC_CANONICAL_HOST
 
 dnl Checks for programs.
-
-AC_PROG_CC
+AC_USE_SYSTEM_EXTENSIONS
+AC_PROG_CC_STDC
+AC_SYS_LARGEFILE
 AC_PROG_INSTALL
 AC_PROG_LN_S
 AC_PROG_YACC
@@ -58,6 +59,7 @@ AC_CHECK_LIB(fl,yywrap,
 
 PKG_CHECK_MODULES([HX], [libHX])
 
+AC_CHECK_FUNCS([__secure_getenv secure_getenv])
 dnl Checks for header files.
 AC_HEADER_DIRENT
 AC_HEADER_STDC
--- at-3.1.13.orig/at.c
+++ at-3.1.13/at.c
@@ -97,6 +97,14 @@
 #define DEFAULT_QUEUE 'a'
 #define BATCH_QUEUE   'b'
 
+#ifndef HAVE_SECURE_GETENV
+#  ifdef HAVE___SECURE_GETENV
+#    define secure_getenv __secure_getenv
+#  else
+#    error neither secure_getenv nor __secure_getenv is available
+#  endif
+#endif
+
 enum {
     ATQ, BATCH, ATRM, AT, CAT
 };				/* what program we want to run */
@@ -359,7 +367,7 @@ writefile(time_t runtimer, char queue)
      */
     mailname = getlogin();
     if (mailname == NULL)
-	mailname = getenv("LOGNAME");
+	    mailname = secure_getenv("LOGNAME");
     if (mailname == NULL || mailname[0] == '\0' || getpwnam(mailname) == NULL) {
 	pass_entry = getpwuid(real_uid);
 	if (pass_entry != NULL)