diff --git a/pkgs/applications/window-managers/oroborus/default.nix b/pkgs/applications/window-managers/oroborus/default.nix
index 275db56dadae..fc2517107670 100644
--- a/pkgs/applications/window-managers/oroborus/default.nix
+++ b/pkgs/applications/window-managers/oroborus/default.nix
@@ -46,6 +46,11 @@ stdenv.mkDerivation rec {
     xorgproto
   ];
 
+  # Workaround build failure on -fno-common toolchains:
+  #   ld: workspaces.o:src/keyboard.h:93: multiple definition of
+  #     `NumLockMask'; client.o:src/keyboard.h:93: first defined here
+  NIX_CFLAGS_COMPILE = "-fcommon";
+
   meta = with lib; {
     homepage = "https://web.archive.org/web/20191129172107/https://www.oroborus.org/";
     description = "A really minimalistic X window manager";