diff --git a/pdfminer/utils.py b/pdfminer/utils.py
index 9cbcbb3..f2258b0 100644
--- a/pdfminer/utils.py
+++ b/pdfminer/utils.py
@@ -145,13 +145,6 @@ def uniq(objs):
     return
 
 
-# csort
-def csort(objs, key):
-    """Order-preserving sorting function."""
-    idxs = dict((obj, i) for (i, obj) in enumerate(objs))
-    return sorted(objs, key=lambda obj: (key(obj), idxs[obj]))
-
-
 # fsplit
 def fsplit(pred, objs):
     """Split a list into two classes according to the predicate."""