diff --git a/ext/um/extconf.rb b/ext/um/extconf.rb
index eba38fa..c515586 100644
--- a/ext/um/extconf.rb
+++ b/ext/um/extconf.rb
@@ -74,7 +74,11 @@ def get_config
 $defs << '-DHAVE_IO_URING_PREP_LISTEN'          if config[:prep_listen]
 $defs << '-DHAVE_IO_URING_SEND_VECTORIZED'      if config[:send_vectoized]
 
-$CFLAGS << ' -Werror -Wall -Wextra'
+# NOTE: -Wall -Wextra enable -Wunused-parameter (https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-W)
+# And -Wunused-parameter throws in:
+# - ruby-4.0.0/ruby/internal/gc.h
+# - ext/um/um.c
+$CFLAGS << ' -Wno-unused-parameter -Werror -Wall -Wextra'
 
 if ENV['SANITIZE']
   $CFLAGS << ' -fsanitize=undefined,address -lasan'