https://bugs.gentoo.org/961098
--- a/src/tint2conf/CMakeLists.txt
+++ b/src/tint2conf/CMakeLists.txt
@@ -75,6 +75,7 @@
                                  ${GTHREAD2_LIBRARIES}
                                  ${GTK3_LIBRARIES}
                                  ${RSVG_LIBRARIES} )
+target_link_libraries( tint2conf m )
 
 add_definitions( -DINSTALL_PREFIX=\"${CMAKE_INSTALL_PREFIX}\" )
 add_definitions( -DLOCALEDIR=\"${CMAKE_INSTALL_FULL_LOCALEDIR}\" )