diff --git a/masque/file/dxf.py b/masque/file/dxf.py
index a0aeaf0..8af24e6 100644
--- a/masque/file/dxf.py
+++ b/masque/file/dxf.py
@@ -18,7 +18,7 @@ import ezdxf
 
 from .utils import is_gzipped, tmpfile
 from .. import Pattern, Ref, PatternError, Label
-from ..library import Library, WrapROLibrary
+from ..library import Library, WrapROLibrary, WrapLibrary
 from ..shapes import Shape, Polygon, Path
 from ..repetition import Grid
 from ..utils import rotation_matrix_2d, layer_t
@@ -148,7 +148,7 @@ def readfile(
         filename: Union[str, pathlib.Path],
         *args,
         **kwargs,
-        ) -> Tuple[Dict[str, Pattern], Dict[str, Any]]:
+        ) -> Tuple[WrapLibrary, Dict[str, Any]]:
     """
     Wrapper for `dxf.read()` that takes a filename or path instead of a stream.
 
@@ -172,7 +172,7 @@ def readfile(
 
 def read(
         stream: TextIO,
-        ) -> Tuple[Dict[str, Pattern], Dict[str, Any]]:
+        ) -> Tuple[WrapLibrary, Dict[str, Any]]:
     """
     Read a dxf file and translate it into a dict of `Pattern` objects. DXF `Block`s are
      translated into `Pattern` objects; `LWPolyline`s are translated into polygons, and `Insert`s
@@ -189,16 +189,19 @@ def read(
     lib = ezdxf.read(stream)
     msp = lib.modelspace()
 
-    npat = _read_block(msp)
-    patterns_dict = dict(
-        [npat] + [_read_block(bb) for bb in lib.blocks if bb.name != '*Model_Space']
-        )
+    top_name, top_pat = _read_block(msp)
+    mlib = WrapLibrary({top_name: top_pat})
+    for bb in lib.blocks:
+        if bb.name == '*Model_Space':
+            continue
+        name, pat = _read_block(bb)
+        mlib[name] = pat
 
     library_info = dict(
         layers=[ll.dxfattribs() for ll in lib.layers],
         )
 
-    return patterns_dict, library_info
+    return mlib, library_info
 
 
 def _read_block(block) -> Tuple[str, Pattern]:
diff --git a/masque/file/gdsii.py b/masque/file/gdsii.py
index c3c5cb0..6b963b6 100644
--- a/masque/file/gdsii.py
+++ b/masque/file/gdsii.py
@@ -161,7 +161,7 @@ def readfile(
         filename: Union[str, pathlib.Path],
         *args,
         **kwargs,
-        ) -> Tuple[Dict[str, Pattern], Dict[str, Any]]:
+        ) -> Tuple[WrapLibrary, Dict[str, Any]]:
     """
     Wrapper for `read()` that takes a filename or path instead of a stream.
 
@@ -186,7 +186,7 @@ def readfile(
 def read(
         stream: IO[bytes],
         raw_mode: bool = True,
-        ) -> Tuple[Dict[str, Pattern], Dict[str, Any]]:
+        ) -> Tuple[WrapLibrary, Dict[str, Any]]:
     """
     # TODO check GDSII file for cycles!
     Read a gdsii file and translate it into a dict of Pattern objects. GDSII structures are
@@ -209,15 +209,15 @@ def read(
     """
     library_info = _read_header(stream)
 
-    patterns_dict = {}
+    mlib = WrapLibrary()
     found_struct = records.BGNSTR.skip_past(stream)
     while found_struct:
         name = records.STRNAME.skip_and_read(stream)
         pat = read_elements(stream, raw_mode=raw_mode)
-        patterns_dict[name.decode('ASCII')] = pat
+        mlib[name.decode('ASCII')] = pat
         found_struct = records.BGNSTR.skip_past(stream)
 
-    return patterns_dict, library_info
+    return mlib, library_info
 
 
 def _read_header(stream: IO[bytes]) -> Dict[str, Any]:
diff --git a/masque/file/oasis.py b/masque/file/oasis.py
index 41383a7..ab34852 100644
--- a/masque/file/oasis.py
+++ b/masque/file/oasis.py
@@ -206,7 +206,7 @@ def readfile(
         filename: Union[str, pathlib.Path],
         *args,
         **kwargs,
-        ) -> Tuple[Dict[str, Pattern], Dict[str, Any]]:
+        ) -> Tuple[WrapLibrary, Dict[str, Any]]:
     """
     Wrapper for `oasis.read()` that takes a filename or path instead of a stream.
 
@@ -230,7 +230,7 @@ def readfile(
 
 def read(
         stream: IO[bytes],
-        ) -> Tuple[Dict[str, Pattern], Dict[str, Any]]:
+        ) -> Tuple[WrapLibrary, Dict[str, Any]]:
     """
     Read a OASIS file and translate it into a dict of Pattern objects. OASIS cells are
      translated into Pattern objects; Polygons are translated into polygons, and Placements
@@ -261,7 +261,7 @@ def read(
         layer_map[str(layer_name.nstring)] = layer_name
     library_info['layer_map'] = layer_map
 
-    patterns_dict = {}
+    mlib = WrapLibrary()
     for cell in lib.cells:
         if isinstance(cell.name, int):
             cell_name = lib.cellnames[cell.name].nstring.string
@@ -463,9 +463,9 @@ def read(
         for placement in cell.placements:
             pat.refs.append(_placement_to_ref(placement, lib))
 
-        patterns_dict[cell_name] = pat
+        mlib[cell_name] = pat
 
-    return patterns_dict, library_info
+    return mlib, library_info
 
 
 def _mlayer2oas(mlayer: layer_t) -> Tuple[int, int]: