diff --git a/lib/csu/powerpc64/Makefile b/lib/csu/powerpc64/Makefile
index dd6e9fb2b501..1c93355b7c48 100644
--- a/lib/csu/powerpc64/Makefile
+++ b/lib/csu/powerpc64/Makefile
@@ -9,6 +9,10 @@ CFLAGS+=	-I${.CURDIR}/../common \
 		-I${.CURDIR}/../../libc/include \
 		-mlongcall
 
+# XXX: See the log for r232932 as to why the above -mlongcall is needed.  Since
+# clang doesn't support -mlongcall, and testing shows a clang linked with a
+# clang-built csu segfaults, this must currently be compiled with gcc.  Once
+# clang supports -mlongcall, or we get a fixed ld, this can be revisited.
 CC:=		gcc
 COMPILER_TYPE:=	gcc