diff --git a/lib/libsetjmp/SOURCES b/lib/libsetjmp/SOURCES
index 33c83275f7..b2f4227930 100644
--- a/lib/libsetjmp/SOURCES
+++ b/lib/libsetjmp/SOURCES
@@ -13,6 +13,7 @@ sh/setjmp.S
 #endif
 
 #ifdef CPU_MIPS
+/* Strangely something seems to do '#define mips 1' */
 #undef mips
 mips/setjmp.S
 #endif