diff --git a/autoconf.spec b/autoconf.spec
index e7781b66492de5ab155772521e6f454b2d6c81b1..31816fd8829eb8308ebc1ef24b77355d0ee53766 100644
--- a/autoconf.spec
+++ b/autoconf.spec
@@ -3,7 +3,7 @@
 
 Name:           autoconf
 Version:        2.71
-Release:        4
+Release:        5
 Summary:        An extensible package to automatically configure software source code packages
 License:        GPLv2+ and GPLv3+ and GFDL-1.3-only
 URL:            https://www.gnu.org/software/%{name}/
@@ -34,6 +34,13 @@ can use, in the form of M4 macro calls.
 
 %prep
 %autosetup -n %{name}-%{version} -p1
+echo 'main() {}' | g++ -E -v - > g++.log 2>&1
+grep -rn -m 1 COLLECT_GCC_OPTIONS g++.log > option.log
+GCC_OPTION=`cat option.log`
+if [[ $GCC_OPTION != *"fsigned-char"* ]];then
+  sed -i "s|((char) -1) < 0|((unsigned char) -1) < 0|g" lib/autoconf/c.m4
+fi
+rm -rf g++.log option.log
 
 %build
 export EMACS=%{_bindir}/emacs
@@ -73,6 +80,9 @@ fi
 
 
 %changelog
+* Tue May 14 2024 Ge Wang <wang__ge@126.com> - 2.71-5
+- Adapt signed-char check macro for default unsigned evironment
+
 * Tue Jul 18 2023 fuanan <fuanan3@h-partners.com> - 2.71-4
 - Type:bugfix
 - ID:NA