diff --git a/src/auto/configure b/src/auto/configure
index e65884c..1628b94 100755
--- a/src/auto/configure
+++ b/src/auto/configure
@@ -12609,7 +12609,7 @@
 	getpgid setpgid setsid sigaltstack sigstack sigset sigsetjmp sigaction \
 	sigprocmask sigvec strcasecmp strerror strftime stricmp strncasecmp \
 	strnicmp strpbrk strtol tgetent towlower towupper iswupper \
-	usleep utime utimes mblen ftruncate
+	usleep utime utimes mblen ftruncate unsetenv
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"