diff --git a/kyotocabinet-configure-c99.patch b/kyotocabinet-configure-c99.patch
new file mode 100644
index 0000000..c332896
--- /dev/null
+++ b/kyotocabinet-configure-c99.patch
@@ -0,0 +1,66 @@
+Avoid implicit ints in the configure script, to prevent checks from
+failing unconditionally with future compilers that do not support
+them by default.
+
+diff --git a/configure b/configure
+index 2dd357d4f253946f..cffa76cdb8d68887 100755
+--- a/configure
++++ b/configure
+@@ -4007,7 +4007,7 @@ $as_echo "#define AC_APPLE_UNIVERSAL_BUILD 1" >>confdefs.h
+ 
+ # System-depending optimization
+ printf 'checking for 64-bit availability... '
+-if printf 'main() {}' | $CC -xc -m64 -o config.tmp - >config.tmp 2>&1
++if printf 'int main(void) {return 0;}' | $CC -xc -m64 -o config.tmp - >config.tmp 2>&1
+ then
+   MYCFLAGS="-m64 $MYCFLAGS"
+   MYCXXFLAGS="-m64 $MYCXXFLAGS"
+@@ -4018,7 +4018,7 @@ fi
+ if test "$enable_opt" != "no"
+ then
+   printf 'checking for CPU optimization availability... '
+-  if printf 'main() {}' | $CC -xc -march=native -o config.tmp - >config.tmp 2>&1
++  if printf 'int main(void) {return 0;}' | $CC -xc -march=native -o config.tmp - >config.tmp 2>&1
+   then
+     MYCFLAGS="-march=native $MYCFLAGS"
+     MYCXXFLAGS="-march=native $MYCXXFLAGS"
+@@ -4028,7 +4028,7 @@ then
+   fi
+ fi
+ printf 'checking for useless warnings... '
+-if printf 'main() {}' | $CC -xc \
++if printf 'int main(void) {return 0;}' | $CC -xc \
+   -Wno-unused-but-set-variable -Wno-unused-but-set-parameter -o config.tmp - >config.tmp 2>&1
+ then
+   MYCFLAGS="$MYCFLAGS -Wno-unused-but-set-variable -Wno-unused-but-set-parameter"
+diff --git a/configure.in b/configure.in
+index 6ce03e3313a211de..5abb5c33281b9da8 100644
+--- a/configure.in
++++ b/configure.in
+@@ -204,7 +204,7 @@ AC_C_BIGENDIAN(MYCPPFLAGS="$MYCPPFLAGS -D_MYBIGEND")
+ 
+ # System-depending optimization
+ printf 'checking for 64-bit availability... '
+-if printf 'main() {}' | $CC -xc -m64 -o config.tmp - >config.tmp 2>&1
++if printf 'int main(void) {return 0;}' | $CC -xc -m64 -o config.tmp - >config.tmp 2>&1
+ then
+   MYCFLAGS="-m64 $MYCFLAGS"
+   MYCXXFLAGS="-m64 $MYCXXFLAGS"
+@@ -215,7 +215,7 @@ fi
+ if test "$enable_opt" != "no"
+ then
+   printf 'checking for CPU optimization availability... '
+-  if printf 'main() {}' | $CC -xc -march=native -o config.tmp - >config.tmp 2>&1
++  if printf 'int main(void) {return 0;}' | $CC -xc -march=native -o config.tmp - >config.tmp 2>&1
+   then
+     MYCFLAGS="-march=native $MYCFLAGS"
+     MYCXXFLAGS="-march=native $MYCXXFLAGS"
+@@ -225,7 +225,7 @@ then
+   fi
+ fi
+ printf 'checking for useless warnings... '
+-if printf 'main() {}' | $CC -xc \
++if printf 'int main(void) {return 0;}' | $CC -xc \
+   -Wno-unused-but-set-variable -Wno-unused-but-set-parameter -o config.tmp - >config.tmp 2>&1
+ then
+   MYCFLAGS="$MYCFLAGS -Wno-unused-but-set-variable -Wno-unused-but-set-parameter"
diff --git a/kyotocabinet.spec b/kyotocabinet.spec
index 6c5abaf..4e540ac 100644
--- a/kyotocabinet.spec
+++ b/kyotocabinet.spec
@@ -1,12 +1,13 @@
 Summary:        A straightforward implementation of DBM
 Name:           kyotocabinet
 Version:        1.2.79
-Release:        2%{?dist}
+Release:        3%{?dist}
 License:        GPLv3
 URL:            https://dbmx.net/%{name}/
 Source:         https://dbmx.net/%{name}/pkg/%{name}-%{version}.tar.gz
 Patch0:         kyotocabinet-1.2.76-cflags.patch
 Patch1:         kyotocabinet-1.2.76-8-byte-atomics.patch
+Patch2: kyotocabinet-configure-c99.patch
 Requires:       %{name}-libs%{?_isa} = %{version}-%{release}
 BuildRequires:  gcc-c++, zlib-devel, lzo-devel, xz-devel
 
@@ -51,6 +52,7 @@ applications that use Kyoto Cabinet.
 %setup -q
 %patch0 -p1 -b .cflags
 %patch1 -p1 -b .8-byte-atomics
+%patch2 -p1
 
 %build
 %configure --disable-opt --enable-lzo --enable-lzma
@@ -140,6 +142,9 @@ make check
 %doc COPYING doc/api/* kyotocabinet.idl
 
 %changelog
+* Wed Apr 12 2023 Florian Weimer <fweimer@redhat.com> - 1.2.79-3
+- Port configure script to C99 (#2186199)
+
 * Thu Jan 19 2023 Fedora Release Engineering <releng@fedoraproject.org> - 1.2.79-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_38_Mass_Rebuild