https://bugs.gentoo.org/925443
https://dev.gnupg.org/T5664
--- a/configure.ac
+++ b/configure.ac
@@ -381,7 +381,10 @@ fi
 AC_SUBST(INSERT_NO_RWLOCK)
 
 case "${host}" in
-    *-*-linux*|*-*-gnu*)
+    *-*-linux-musl*)
+        INSERT_EXPOSE_RWLOCK_API="1"
+        ;;
+    *-*-linux-gnu*|*-*-gnu*)
         INSERT_EXPOSE_RWLOCK_API="defined(__USE_UNIX98) || defined(__USE_XOPEN2K)"
         ;;
     *)