diff --git a/README b/README
index d966b7f..0d92a0a 100755
--- a/README
+++ b/README
@@ -42,6 +42,10 @@ mkfifo
 sh
 wc
 
+The following sh built-ins are working, but not complete or POSIX-compliant:
+kill
+umask
+
 Building
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