diff --git a/secop/datatypes.py b/secop/datatypes.py
index 885ccd2..634f4af 100644
--- a/secop/datatypes.py
+++ b/secop/datatypes.py
@@ -278,7 +278,7 @@ class StringType(DataType):
         if self.minsize:
             return 'StringType(%s, %s)' % (
                 str(self.minsize) or 'unspecified', str(self.maxsize) or 'unspecified')
-        return 'StringType(%d)' % str(self.maxsize)
+        return 'StringType(%s)' % str(self.maxsize)
 
     def validate(self, value):
         """return the validated (internal) value or raise"""
diff --git a/secop_mlz/entangle.py b/secop_mlz/entangle.py
index bf323c5..4887d69 100644
--- a/secop_mlz/entangle.py
+++ b/secop_mlz/entangle.py
@@ -971,9 +971,9 @@ class StringIO(PyTangoDevice, Module):
                 ArrayOf(
                     TupleOf(
                         StringType(),
-                        IntRange()))],
+                        IntRange()),100)],
             result=ArrayOf(
-                StringType())),
+                StringType(),100)),
     }
 
     def do_communicate(self, value=StringType()):