diff -pruN 2.4.12-5/debian/changelog 2.4.12-5ubuntu1/debian/changelog
--- 2.4.12-5/debian/changelog	2023-02-07 21:42:22.000000000 +0000
+++ 2.4.12-5ubuntu1/debian/changelog	2023-02-18 09:31:12.000000000 +0000
@@ -1,3 +1,9 @@
+opendht (2.4.12-5ubuntu1) lunar; urgency=medium
+
+  * Mark some symbols optional to avoid FTBFS with LTO enabled
+
+ -- Graham Inggs <ginggs@ubuntu.com>  Sat, 18 Feb 2023 09:31:12 +0000
+
 opendht (2.4.12-5) unstable; urgency=medium
 
   [ Amin Bandali ]
diff -pruN 2.4.12-5/debian/control 2.4.12-5ubuntu1/debian/control
--- 2.4.12-5/debian/control	2023-02-07 07:30:18.000000000 +0000
+++ 2.4.12-5ubuntu1/debian/control	2023-02-18 08:45:22.000000000 +0000
@@ -1,7 +1,8 @@
 Source: opendht
 Section: libs
 Priority: optional
-Maintainer: Alexandre Viau <aviau@debian.org>
+Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
+XSBC-Original-Maintainer: Alexandre Viau <aviau@debian.org>
 Uploaders: Amin Bandali <bandali@gnu.org>
 Build-Depends: debhelper-compat (= 12),
                cmake,
diff -pruN 2.4.12-5/debian/libopendht-c2.symbols 2.4.12-5ubuntu1/debian/libopendht-c2.symbols
--- 2.4.12-5/debian/libopendht-c2.symbols	2023-02-07 21:38:29.000000000 +0000
+++ 2.4.12-5ubuntu1/debian/libopendht-c2.symbols	2023-02-18 08:45:17.000000000 +0000
@@ -1,11 +1,11 @@
 libopendht-c.so.2 libopendht-c2 #MINVER#
- _ZNSt12_Vector_baseIhSaIhEED1Ev@Base 2.4.12
- _ZNSt12_Vector_baseIhSaIhEED2Ev@Base 2.4.12
- _ZNSt14_Function_baseD1Ev@Base 2.4.12
- _ZNSt14_Function_baseD2Ev@Base 2.4.12
+ (optional=lto)_ZNSt12_Vector_baseIhSaIhEED1Ev@Base 2.4.12
+ (optional=lto)_ZNSt12_Vector_baseIhSaIhEED2Ev@Base 2.4.12
+ (optional=lto)_ZNSt14_Function_baseD1Ev@Base 2.4.12
+ (optional=lto)_ZNSt14_Function_baseD2Ev@Base 2.4.12
  (arch=armel riscv64)_ZNSt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE1EE10_M_releaseEv@Base 2.4.12
- (arch=!armel !riscv64)_ZNSt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EE10_M_releaseEv@Base 2.4.12
- (arch=!armel !armhf !i386 !mipsel !hppa !m68k !powerpc !riscv64 !sparc64 !x32)_ZNSt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EE24_M_release_last_use_coldEv@Base 2.4.12
+ (optional=lto|arch=!armel !riscv64)_ZNSt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EE10_M_releaseEv@Base 2.4.12
+ (optional=lto|arch=!armel !armhf !i386 !mipsel !hppa !m68k !powerpc !riscv64 !sparc64 !x32)_ZNSt16_Sp_counted_baseILN9__gnu_cxx12_Lock_policyE2EE24_M_release_last_use_coldEv@Base 2.4.12
  (arch=riscv64)_ZTIN9__gnu_cxx7__mutexE@Base 2.4.12
  (arch=riscv64)_ZTISt11_Mutex_baseILN9__gnu_cxx12_Lock_policyE1EE@Base 2.4.12
  (arch=!armel !riscv64)_ZTISt11_Mutex_baseILN9__gnu_cxx12_Lock_policyE2EE@Base 2.4.12