diff --git a/shared/key-request.sh b/shared/key-request.sh
index 3e16db9c..9d0da525 100644
--- a/shared/key-request.sh
+++ b/shared/key-request.sh
@@ -92,9 +92,8 @@ print(v)
             fi
             # SECURITY: val is already validated against ^[a-zA-Z0-9._/@-]+$ above,
             # and var_name is validated against ^[A-Z_][A-Z0-9_]*$ by the caller.
-            # Use printf -v for safe variable assignment (no command substitution/expansion).
-            printf -v "${var_name}" '%s' "${val}"
-            export "${var_name}"
+            # Use export NAME=VALUE (bash 3.2 compatible; printf -v requires bash 4.0+).
+            export "${var_name}=${val}"
             return 0
         fi
     fi