if(${ENABLE_erd})
    find_package(erd 3.0.6 CONFIG QUIET)

    if(${erd_FOUND})
        get_property(_loc TARGET erd::erd PROPERTY LOCATION)
        message(STATUS "${Cyan}Found erd${ColourReset}: ${_loc} (found version ${erd_VERSION})")
        add_library(erd_external INTERFACE)  # dummy
    else()
        if(${CMAKE_INSIST_FIND_PACKAGE_erd})
            message(FATAL_ERROR "Suitable erd could not be externally located as user insists")
        endif()

        include(ExternalProject)
        message(STATUS "Suitable erd could not be located, ${Magenta}Building erd${ColourReset} instead.")
        ExternalProject_Add(erd_external
            GIT_REPOSITORY https://github.com/psi4/erd
            GIT_TAG v3.0.6
            UPDATE_COMMAND ""
            CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
                       -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
                       -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
                       -DCMAKE_Fortran_COMPILER=${CMAKE_Fortran_COMPILER}
                       -DCMAKE_INSTALL_LIBDIR=${CMAKE_INSTALL_LIBDIR}
                       -DCMAKE_INSTALL_INCLUDEDIR=${CMAKE_INSTALL_INCLUDEDIR}
                       -DBUILD_SHARED_LIBS=${BUILD_SHARED_LIBS}
                       -DENABLE_OPENMP=${ENABLE_OPENMP}  # relevant for thread safety
                       -DENABLE_XHOST=${ENABLE_XHOST}
                       -DBUILD_FPIC=${BUILD_FPIC}
                       -DENABLE_GENERIC=${ENABLE_GENERIC}
                       -DLIBC_INTERJECT=${LIBC_INTERJECT}
            CMAKE_CACHE_ARGS -DCMAKE_Fortran_FLAGS:STRING=${CMAKE_Fortran_FLAGS}
                             -DCMAKE_C_FLAGS:STRING=${CMAKE_C_FLAGS}
            INSTALL_COMMAND DESTDIR=${CMAKE_BINARY_DIR}/stage ${CMAKE_MAKE_PROGRAM} install)

        set(erd_DIR ${STAGED_INSTALL_PREFIX}/share/cmake/erd CACHE PATH "path to internally built erdConfig.cmake" FORCE)
    endif()
else()
    add_library(erd_external INTERFACE)  # dummy
endif()

