diff --git a/beets/library.py b/beets/library.py
index 0f9fddafe..9d2a1b857 100644
--- a/beets/library.py
+++ b/beets/library.py
@@ -60,6 +60,8 @@ class PathQuery(dbcore.FieldQuery):
         """
         super(PathQuery, self).__init__(field, pattern, fast)
 
+        # By default, the case sensitivity depends on the filesystem
+        # the library is located on.
         if case_sensitive is None:
             case_sensitive = beets.util.is_filesystem_case_sensitive(
                 beets.config['directory'].get())
diff --git a/beets/util/__init__.py b/beets/util/__init__.py
index f0304fc45..ed1320807 100644
--- a/beets/util/__init__.py
+++ b/beets/util/__init__.py
@@ -762,6 +762,13 @@ def interactive_open(target, command=None):
 
 
 def is_filesystem_case_sensitive(path):
+    """Checks if the filesystem at the given path is case sensitive.
+    If the path does not exist, a case sensitive file system is
+    assumed if the system is not windows.
+
+    :param path: The path to check for case sensitivity.
+    :return: True if the file system is case sensitive, False else.
+    """
     if os.path.exists(path):
         # Check if the path to the library exists in lower and upper case
         if os.path.exists(path.lower()) and \