diff --git a/src/type/bool_type.h b/src/type/bool_type.h
index fa3f01da45..cc35062187 100644
--- a/src/type/bool_type.h
+++ b/src/type/bool_type.h
@@ -19,6 +19,12 @@
 
 #include "src/type/type.h"
 
+// X11 likes to #define Bool leading to confusing error messages.
+// If its defined, undefine it.
+#ifdef Bool
+#undef Bool
+#endif
+
 namespace tint {
 namespace type {