diff --git b/cola/diffparse.py a/cola/diffparse.py
index 33a892e..a680f4b 100644
--- b/cola/diffparse.py
+++ a/cola/diffparse.py
@@ -6,21 +6,10 @@ from cola import gitcmds
 from cola import gitcfg
 
 
-class DiffSource(object):
-    def get(self, head, amending, filename, cached, reverse):
-        return gitcmds.diff_helper(head=head,
-                                   amending=amending,
-                                   filename=filename,
-                                   with_diff_header=True,
-                                   cached=cached,
-                                   reverse=reverse)
-
-
 class DiffParser(object):
     """Handles parsing diff for use by the interactive index editor."""
     def __init__(self, model, filename='',
-                 cached=True, reverse=False,
-                 diff_source=None):
+                 cached=True, reverse=False):
 
         self._header_re = re.compile('^@@ -(\d+),(\d+) \+(\d+),(\d+) @@.*')
         self._header_start_re = re.compile('^@@ -(\d+) \+(\d+),(\d+) @@.*')
@@ -40,11 +29,13 @@ class DiffParser(object):
         self.diff_sel = []
         self.selected = []
         self.filename = filename
-        self.diff_source = diff_source or DiffSource()
 
-        (header, diff) = self.diff_source.get(self.head, self.amending,
-                                              filename, cached,
-                                              cached or reverse)
+        (header, diff) = gitcmds.diff_helper(head=self.head,
+                                             amending=self.amending,
+                                             filename=filename,
+                                             with_diff_header=True,
+                                             cached=cached,
+                                             reverse=cached or reverse)
         self.model = model
         self.diff = diff
         self.header = header
@@ -52,10 +43,11 @@ class DiffParser(object):
 
         # Always index into the non-reversed diff
         self.fwd_header, self.fwd_diff = \
-                self.diff_source.get(self.head,
-                                     self.amending,
-                                     filename,
-                                     cached, False)
+            gitcmds.diff_helper(head=self.head,
+                                amending=self.amending,
+                                filename=filename,
+                                with_diff_header=True,
+                                cached=cached)
 
     def write_diff(self,filename,which,selected=False,noop=False):
         """Writes a new diff corresponding to the user's selection."""
