diff --git a/SC2155.md b/SC2155.md
index 25e5e94..d6f2fb9 100644
--- a/SC2155.md
+++ b/SC2155.md
@@ -21,3 +21,5 @@ If you intend to ignore the return value of an assignment, you can either ignore
 
     export foo
     foo=$(mycmd) || true
+
+Shellcheck does not warn about `export foo=bar` because `bar` is a literal and not a command substitution with an independent return value. It also does not warn about `local -r foo=$(cmd)`, where declaration and assignment must be in the same command.
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