diff --git a/git-difftool.perl b/git-difftool.perl
index a5790d03a0..959822d5f3 100755
--- a/git-difftool.perl
+++ b/git-difftool.perl
@@ -182,6 +182,10 @@ EOF
 		}
 	}
 
+	# Go to the root of the worktree so that the left index files
+	# are properly setup -- the index is toplevel-relative.
+	chdir($workdir);
+
 	# Setup temp directories
 	my $tmpdir = tempdir('git-difftool.XXXXX', CLEANUP => 0, TMPDIR => 1);
 	my $ldir = "$tmpdir/left";
diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index 70a2de461a..99d4123461 100755
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -374,6 +374,7 @@ test_expect_success PERL 'setup change in subdirectory' '
 	echo master >sub/sub &&
 	git add sub/sub &&
 	git commit -m "added sub/sub" &&
+	git tag v1 &&
 	echo test >>file &&
 	echo test >>sub/sub &&
 	git add file sub/sub &&
@@ -409,12 +410,49 @@ run_dir_diff_test 'difftool --dir-diff ignores --prompt' '
 	grep file output
 '
 
-run_dir_diff_test 'difftool --dir-diff from subdirectory' '
+run_dir_diff_test 'difftool --dir-diff branch from subdirectory' '
 	(
 		cd sub &&
 		git difftool --dir-diff $symlinks --extcmd ls branch >output &&
-		grep sub output &&
-		grep file output
+		# "sub" must only exist in "right"
+		# "file" and "file2" must be listed in both "left" and "right"
+		test "1" = $(grep sub output | wc -l) &&
+		test "2" = $(grep file"$" output | wc -l) &&
+		test "2" = $(grep file2 output | wc -l)
+	)
+'
+
+run_dir_diff_test 'difftool --dir-diff v1 from subdirectory' '
+	(
+		cd sub &&
+		git difftool --dir-diff $symlinks --extcmd ls v1 >output &&
+		# "sub" and "file" exist in both v1 and HEAD.
+		# "file2" is unchanged.
+		test "2" = $(grep sub output | wc -l) &&
+		test "2" = $(grep file output | wc -l) &&
+		test "0" = $(grep file2 output | wc -l)
+	)
+'
+
+run_dir_diff_test 'difftool --dir-diff branch from subdirectory w/ pathspec' '
+	(
+		cd sub &&
+		git difftool --dir-diff $symlinks --extcmd ls branch -- .>output &&
+		# "sub" only exists in "right"
+		# "file" and "file2" must not be listed
+		test "1" = $(grep sub output | wc -l) &&
+		test "0" = $(grep file output | wc -l)
+	)
+'
+
+run_dir_diff_test 'difftool --dir-diff v1 from subdirectory w/ pathspec' '
+	(
+		cd sub &&
+		git difftool --dir-diff $symlinks --extcmd ls v1 -- .>output &&
+		# "sub" exists in v1 and HEAD
+		# "file" is filtered out by the pathspec
+		test "2" = $(grep sub output | wc -l) &&
+		test "0" = $(grep file output | wc -l)
 	)
 '