diff --git a/logging.sh b/logging.sh
index dc16988..dd97c29 100644
--- a/logging.sh
+++ b/logging.sh
@@ -53,7 +53,7 @@
 # Version (updated by release workflow)
 # Guard against re-initialization when sourced multiple times
 # Use readonly status instead of emptiness to avoid environment bypass
-if ! readonly -p 2>/dev/null | grep -q "declare -[^ ]*r[^ ]* BASH_LOGGER_VERSION="; then
+if ! readonly -p 2>/dev/null | grep -qE '(declare|typeset) -[^ ]*r[^ ]* BASH_LOGGER_VERSION='; then
     readonly BASH_LOGGER_VERSION="2.5.1"
 
     # Unset potentially malicious environment variables before setting internal constants