diff --git a/diff-lib.c b/diff-lib.c
index 392ce2bef0..a98385538c 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -183,7 +183,7 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 			 * Show the diff for the 'ce' if we found the one
 			 * from the desired stage.
 			 */
-			diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
+			diff_unmerge(&revs->diffopt, ce->name);
 			if (ce_stage(ce) != diff_unmerged_stage)
 				continue;
 		}
@@ -372,8 +372,9 @@ static void do_oneway_diff(struct unpack_trees_options *o,
 	match_missing = !revs->ignore_merges;
 
 	if (cached && idx && ce_stage(idx)) {
-		diff_unmerge(&revs->diffopt, idx->name, idx->ce_mode,
-			     idx->sha1);
+		struct diff_filepair *pair;
+		pair = diff_unmerge(&revs->diffopt, idx->name);
+		fill_filespec(pair->one, idx->sha1, idx->ce_mode);
 		return;
 	}
 
diff --git a/diff.c b/diff.c
index 4c34c64bd7..d2c5c563bc 100644
--- a/diff.c
+++ b/diff.c
@@ -4308,9 +4308,7 @@ void diff_change(struct diff_options *options,
 		DIFF_OPT_SET(options, HAS_CHANGES);
 }
 
-struct diff_filepair *diff_unmerge(struct diff_options *options,
-				   const char *path,
-				   unsigned mode, const unsigned char *sha1)
+struct diff_filepair *diff_unmerge(struct diff_options *options, const char *path)
 {
 	struct diff_filepair *pair;
 	struct diff_filespec *one, *two;
@@ -4321,7 +4319,6 @@ struct diff_filepair *diff_unmerge(struct diff_options *options,
 
 	one = alloc_filespec(path);
 	two = alloc_filespec(path);
-	fill_filespec(one, sha1, mode);
 	pair = diff_queue(&diff_queued_diff, one, two);
 	pair->is_unmerged = 1;
 	return pair;
diff --git a/diff.h b/diff.h
index f51a8ee1b2..3edb705b4d 100644
--- a/diff.h
+++ b/diff.h
@@ -209,10 +209,7 @@ extern void diff_change(struct diff_options *,
 			const char *fullpath,
 			unsigned dirty_submodule1, unsigned dirty_submodule2);
 
-extern struct diff_filepair *diff_unmerge(struct diff_options *,
-			 const char *path,
-			 unsigned mode,
-			 const unsigned char *sha1);
+extern struct diff_filepair *diff_unmerge(struct diff_options *, const char *path);
 
 #define DIFF_SETUP_REVERSE      	1
 #define DIFF_SETUP_USE_CACHE		2