diff --git a/riscv_rules.hancho b/riscv_rules.hancho
index 8443d65..a4de10a 100644
--- a/riscv_rules.hancho
+++ b/riscv_rules.hancho
@@ -10,11 +10,14 @@ rv_config = hancho.Config(
         "-MMD"
     ],
     rv_opt_mode = "-O0",
+    joined_warnings = "{join_prefix('-W', get('warnings', []))}",
+    joined_defines  = "{join_prefix('-D', get('defines', []))}",
+    joined_includes = "{join_prefix('-I', get('includes', []))}",
 )
 
 rv_compile = hancho.Command(
     rv_config,
-    command = "{rv_toolchain}-g++ {rv_flags_c} -c {in_src} -o {out_obj}",
+    command = "{rv_toolchain}-g++ {rv_flags_c} {joined_warnings} {joined_defines} {joined_includes} -c {in_src} -o {out_obj}",
     out_obj = "{swap_ext(in_src, '.o')}",
     c_deps  = "{swap_ext(in_src, '.d')}",
 )
@@ -22,8 +25,7 @@ rv_compile = hancho.Command(
 rv_link = hancho.Command(
     rv_config,
     command = "{rv_toolchain}-gcc {rv_flags_c} {in_objs} -o {out_bin} -lgcc",
-    rv_flags_c = [
-        rv_config.rv_flags_c,
+    rv_flags_c = rv_config.rv_flags_c + [
         "-nostdlib",
         "-nostartfiles",
         "-Wl,-T {linkerscript}",