diff --git a/testframework.sh b/testframework.sh
index d6f4eca9..e84543e8 100644
--- a/testframework.sh
+++ b/testframework.sh
@@ -345,7 +345,7 @@ _tfw_shellarg() {
    _tfw_shopt -s extglob
    for arg; do
       case "$arg" in
-      +([A-Za-z_0-9.,+\/-])) shellarg+=("$arg");;
+      +([A-Za-z_0-9.,:=+\/-])) shellarg+=("$arg");;
       *) shellarg+=("'${arg//'/'\\''}'");;
       esac
    done