diff --color -Naur groff-1.22.4.orig/gnulib_m4/signbit.m4 groff-1.22.4/gnulib_m4/signbit.m4
--- groff-1.22.4.orig/gnulib_m4/signbit.m4	2018-12-23 09:34:15.000000000 -0500
+++ groff-1.22.4/gnulib_m4/signbit.m4	2021-03-09 13:32:45.593225230 -0500
@@ -31,6 +31,8 @@
         [case "$host_os" in
                           # Guess yes on glibc systems.
            *-gnu* | gnu*) gl_cv_func_signbit="guessing yes" ;;
+                          # Guess yes on musl systems.
+           *-musl*)       gl_cv_func_signbit="guessing yes" ;;
                           # Guess yes on native Windows.
            mingw*)        gl_cv_func_signbit="guessing yes" ;;
                           # If we don't know, assume the worst.