diff --git a/quantum/keymap_extras/keymap_fr_ch.h b/quantum/keymap_extras/keymap_fr_ch.h
index 02ee22a12e8..783880c113d 100644
--- a/quantum/keymap_extras/keymap_fr_ch.h
+++ b/quantum/keymap_extras/keymap_fr_ch.h
@@ -20,6 +20,11 @@
 
 // clang-format off
 
+#ifdef CH_H
+// The ChibiOS ch.h file defines this...
+#    undef CH_H
+#endif
+
 /*
  * ┌───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───┬───────┐
  * │ § │ 1 │ 2 │ 3 │ 4 │ 5 │ 6 │ 7 │ 8 │ 9 │ 0 │ ' │ ^ │       │