diff --git a/beets/library.py b/beets/library.py
index 1d63da2c7..18764b6f0 100644
--- a/beets/library.py
+++ b/beets/library.py
@@ -40,7 +40,7 @@ import beets
 # `memoryview`, depending on the Python version, tells it that we
 # actually mean non-text data.
 if six.PY2:
-    BLOB_TYPE = buffer
+    BLOB_TYPE = buffer  # noqa ignore=F821
 else:
     BLOB_TYPE = memoryview
 
diff --git a/beets/util/__init__.py b/beets/util/__init__.py
index 0715459af..fec6d56db 100644
--- a/beets/util/__init__.py
+++ b/beets/util/__init__.py
@@ -654,7 +654,7 @@ def as_string(value):
     """
     buffer_types = memoryview
     if six.PY2:
-        buffer_types = (buffer, memoryview)
+        buffer_types = (buffer, memoryview)  # noqa ignore=F821
 
     if value is None:
         return u''