diff --git a/masque/file/gdsii.py b/masque/file/gdsii.py
index c20200c..f589ad8 100644
--- a/masque/file/gdsii.py
+++ b/masque/file/gdsii.py
@@ -617,7 +617,12 @@ def load_libraryfile(
             stream = mmap.mmap(base_stream.fileno(), 0, access=mmap.ACCESS_READ)    # type: ignore
         else:
             stream = path.open(mode='rb')          # noqa: SIM115
-    return load_library(stream, full_load=full_load, postprocess=postprocess)
+
+    try:
+        return load_library(stream, full_load=full_load, postprocess=postprocess)
+    finally:
+        if full_load:
+            stream.close()
 
 
 def check_valid_names(