diff --git a/src/PWscf/input.jl b/src/PWscf/input.jl
index ae09814..d512258 100644
--- a/src/PWscf/input.jl
+++ b/src/PWscf/input.jl
@@ -66,7 +66,7 @@ const ATOMIC_POSITIONS_BLOCK = r"""
const CELL_PARAMETERS_BLOCK = r"""
^[ \t]*
CELL_PARAMETERS [ \t]*
-[{(]? [ \t]* (?P