diff --git a/builtin-merge.c b/builtin-merge.c
index a201c6628d..b280444e10 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -564,8 +564,6 @@ static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
 	struct dir_struct dir;
 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 
-	if (read_cache_unmerged())
-		die("you need to resolve your current index first");
 	refresh_cache(REFRESH_QUIET);
 
 	fd = hold_locked_index(lock_file, 1);
@@ -651,13 +649,15 @@ static void add_strategies(const char *string, unsigned attr)
 static int merge_trivial(void)
 {
 	unsigned char result_tree[20], result_commit[20];
-	struct commit_list parent;
+	struct commit_list *parent = xmalloc(sizeof(struct commit_list *));
 
 	write_tree_trivial(result_tree);
 	printf("Wonderful.\n");
-	parent.item = remoteheads->item;
-	parent.next = NULL;
-	commit_tree(merge_msg.buf, result_tree, &parent, result_commit);
+	parent->item = lookup_commit(head);
+	parent->next = xmalloc(sizeof(struct commit_list *));
+	parent->next->item = remoteheads->item;
+	parent->next->next = NULL;
+	commit_tree(merge_msg.buf, result_tree, parent, result_commit);
 	finish(result_commit, "In-index merge");
 	drop_save();
 	return 0;
@@ -743,6 +743,7 @@ static int evaluate_result(void)
 	int cnt = 0;
 	struct rev_info rev;
 
+	discard_cache();
 	if (read_cache() < 0)
 		die("failed to read the cache");
 
@@ -776,7 +777,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	struct commit_list **remotes = &remoteheads;
 
 	setup_work_tree();
-	if (unmerged_cache())
+	if (read_cache_unmerged())
 		die("You are in the middle of a conflicted merge.");
 
 	/*
@@ -1073,6 +1074,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		}
 
 		/* Automerge succeeded. */
+		discard_cache();
 		write_tree_trivial(result_tree);
 		automerge_was_ok = 1;
 		break;
diff --git a/t/t3030-merge-recursive.sh b/t/t3030-merge-recursive.sh
index aff360303a..f2880152b0 100755
--- a/t/t3030-merge-recursive.sh
+++ b/t/t3030-merge-recursive.sh
@@ -269,6 +269,17 @@ test_expect_success 'merge-recursive result' '
 
 '
 
+test_expect_success 'fail if the index has unresolved entries' '
+
+	rm -fr [abcd] &&
+	git checkout -f "$c1" &&
+
+	test_must_fail git merge "$c5" &&
+	test_must_fail git merge "$c5" 2> out &&
+	grep "You are in the middle of a conflicted merge" out
+
+'
+
 test_expect_success 'merge-recursive remove conflict' '
 
 	rm -fr [abcd] &&
diff --git a/t/t7600-merge.sh b/t/t7600-merge.sh
index fee8fb77d4..dbc90bc416 100755
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@ -498,4 +498,13 @@ test_expect_success 'merge fast-forward in a dirty tree' '
 
 test_debug 'gitk --all'
 
+test_expect_success 'in-index merge' '
+	git reset --hard c0 &&
+	git merge --no-ff -s resolve c1 > out &&
+	grep "Wonderful." out &&
+	verify_parents $c0 $c1
+'
+
+test_debug 'gitk --all'
+
 test_done
diff --git a/t/t7605-merge-resolve.sh b/t/t7605-merge-resolve.sh
index ee21a107fd..f1f86ddb23 100755
--- a/t/t7605-merge-resolve.sh
+++ b/t/t7605-merge-resolve.sh
@@ -36,7 +36,9 @@ test_expect_success 'merge c1 to c2' '
 	git diff --exit-code &&
 	test -f c0.c &&
 	test -f c1.c &&
-	test -f c2.c
+	test -f c2.c &&
+	test 3 = $(git ls-tree -r HEAD | wc -l) &&
+	test 3 = $(git ls-files | wc -l)
 '
 
 test_expect_success 'merge c2 to c3 (fails)' '