@@ -653,7 +653,8 @@ EOH

                 *)

                     completion_source="$FGDIR/install/flightgear/share/zsh/site-functions/_fgfs"

                     if test -r "$completion_source"; then

-                        if egrep --quiet "^\s*'${fgfs_arg%=*}=?\[" "$completion_source"; then

+                        if egrep --quiet "^\s*'(${fgfs_arg%=*}=?|)\[" "$completion_source" \

+                        || [[ ${fgfs_arg} =~ ^--prop(:(string|double|float|long|int|bool))?:/[[:print:]]+= ]]; then

                             fgfs_args+=($fgfs_arg)

                         else

                             echo unknown option: ${fgfs_arg%=*}