diff --git a/Rsconscript b/Rsconscript
index 767264a..8c3f2de 100644
--- a/Rsconscript
+++ b/Rsconscript
@@ -9,6 +9,7 @@ build do
     env["LIBS"] += %w[X11 GLX]
     env["sources"] = glob("src/**/*.{c,d}")
     env["D_IMPORT_PATH"] += glob("src/**")
+    env["DFLAGS"] += %w[-Wall]
     env.Program("jes", "${sources}")
   end
   main_env.clone do |env|