Index: frontends/slang/CMakeLists.txt
--- frontends/slang/CMakeLists.txt.orig
+++ frontends/slang/CMakeLists.txt
@@ -2,6 +2,7 @@ include(lib/cmake/GitRevision.cmake)
 git_rev_parse(YOSYS_SLANG_REVISION ${CMAKE_CURRENT_SOURCE_DIR}/lib)
 git_rev_parse(SLANG_REVISION ${PROJECT_SOURCE_DIR}/libs/slang)
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/lib/src/version.h.in ${CMAKE_CURRENT_BINARY_DIR}/version.h)
+add_compile_definitions(FMT_DEPRECATED_HEAVY_CORE)
 
 yosys_frontend(slang
 	lib/src/abort_helpers.cc
