diff --git a/builtin/grep.c b/builtin/grep.c
index bad9c0a..6fb93c0 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -566,7 +566,7 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 		strbuf_add(base, entry.path, te_len);
 
 		if (S_ISREG(entry.mode)) {
-			hit |= grep_oid(opt, entry.oid, base->buf, tn_len,
+			hit |= grep_oid(opt, &entry.oid, base->buf, tn_len,
 					 check_attr ? base->buf + tn_len : NULL);
 		} else if (S_ISDIR(entry.mode)) {
 			enum object_type type;
@@ -574,10 +574,10 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 			void *data;
 			unsigned long size;
 
-			data = lock_and_read_oid_file(entry.oid, &type, &size);
+			data = lock_and_read_oid_file(&entry.oid, &type, &size);
 			if (!data)
 				die(_("unable to read tree (%s)"),
-				    oid_to_hex(entry.oid));
+				    oid_to_hex(&entry.oid));
 
 			strbuf_addch(base, '/');
 			init_tree_desc(&sub, data, size);
@@ -585,7 +585,7 @@ static int grep_tree(struct grep_opt *opt, const struct pathspec *pathspec,
 					 check_attr, repo);
 			free(data);
 		} else if (recurse_submodules && S_ISGITLINK(entry.mode)) {
-			hit |= grep_submodule(opt, repo, pathspec, entry.oid,
+			hit |= grep_submodule(opt, repo, pathspec, &entry.oid,
 					      base->buf, base->buf + tn_len);
 		}
 
diff --git a/builtin/merge-tree.c b/builtin/merge-tree.c
index 70f6fc9..4500c41 100644
--- a/builtin/merge-tree.c
+++ b/builtin/merge-tree.c
@@ -154,15 +154,15 @@ static void show_result(void)
 /* An empty entry never compares same, not even to another empty entry */
 static int same_entry(struct name_entry *a, struct name_entry *b)
 {
-	return	a->oid &&
-		b->oid &&
-		oideq(a->oid, b->oid) &&
+	return	!is_null_oid(&a->oid) &&
+		!is_null_oid(&b->oid) &&
+		oideq(&a->oid, &b->oid) &&
 		a->mode == b->mode;
 }
 
 static int both_empty(struct name_entry *a, struct name_entry *b)
 {
-	return !(a->oid || b->oid);
+	return is_null_oid(&a->oid) && is_null_oid(&b->oid);
 }
 
 static struct merge_list *create_entry(unsigned stage, unsigned mode, const struct object_id *oid, const char *path)
@@ -178,7 +178,7 @@ static struct merge_list *create_entry(unsigned stage, unsigned mode, const stru
 
 static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
 {
-	char *path = xmallocz(traverse_path_len(info, n));
+	char *path = xmallocz(traverse_path_len(info, n) + the_hash_algo->rawsz);
 	return make_traverse_path(path, info, n);
 }
 
@@ -192,8 +192,8 @@ static void resolve(const struct traverse_info *info, struct name_entry *ours, s
 		return;
 
 	path = traverse_path(info, result);
-	orig = create_entry(2, ours->mode, ours->oid, path);
-	final = create_entry(0, result->mode, result->oid, path);
+	orig = create_entry(2, ours->mode, &ours->oid, path);
+	final = create_entry(0, result->mode, &result->oid, path);
 
 	final->link = orig;
 
@@ -217,7 +217,7 @@ static void unresolved_directory(const struct traverse_info *info,
 
 	newbase = traverse_path(info, p);
 
-#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? (e)->oid : NULL)
+#define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
 	buf0 = fill_tree_descriptor(t + 0, ENTRY_OID(n + 0));
 	buf1 = fill_tree_descriptor(t + 1, ENTRY_OID(n + 1));
 	buf2 = fill_tree_descriptor(t + 2, ENTRY_OID(n + 2));
@@ -243,7 +243,7 @@ static struct merge_list *link_entry(unsigned stage, const struct traverse_info
 		path = entry->path;
 	else
 		path = traverse_path(info, n);
-	link = create_entry(stage, n->mode, n->oid, path);
+	link = create_entry(stage, n->mode, &n->oid, path);
 	link->link = entry;
 	return link;
 }
@@ -318,7 +318,7 @@ static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, s
 	}
 
 	if (same_entry(entry+0, entry+1)) {
-		if (entry[2].oid && !S_ISDIR(entry[2].mode)) {
+		if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
 			/* We did not touch, they modified -- take theirs */
 			resolve(info, entry+1, entry+2);
 			return mask;
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 24bba81..327d917 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -1334,7 +1334,7 @@ static void add_pbase_object(struct tree_desc *tree,
 		if (cmp < 0)
 			return;
 		if (name[cmplen] != '/') {
-			add_object_entry(entry.oid,
+			add_object_entry(&entry.oid,
 					 object_type(entry.mode),
 					 fullname, 1);
 			return;
@@ -1345,7 +1345,7 @@ static void add_pbase_object(struct tree_desc *tree,
 			const char *down = name+cmplen+1;
 			int downlen = name_cmp_len(down);
 
-			tree = pbase_tree_get(entry.oid);
+			tree = pbase_tree_get(&entry.oid);
 			if (!tree)
 				return;
 			init_tree_desc(&sub, tree->tree_data, tree->tree_size);
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 64a8df4..1f1010e 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -94,8 +94,8 @@ static int tree_is_complete(const struct object_id *oid)
 	init_tree_desc(&desc, tree->buffer, tree->size);
 	complete = 1;
 	while (tree_entry(&desc, &entry)) {
-		if (!has_sha1_file(entry.oid->hash) ||
-		    (S_ISDIR(entry.mode) && !tree_is_complete(entry.oid))) {
+		if (!has_sha1_file(entry.oid.hash) ||
+		    (S_ISDIR(entry.mode) && !tree_is_complete(&entry.oid))) {
 			tree->object.flags |= INCOMPLETE;
 			complete = 0;
 		}