diff --git a/builtin-checkout.c b/builtin-checkout.c
index 05eee4ecc7..25845cdd5e 100644
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -269,8 +269,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 		}
 
 		/* 2-way merge to the new branch */
-		topts.initial_checkout = (!active_nr &&
-					  (old->commit == new->commit));
+		topts.initial_checkout = is_cache_unborn();
 		topts.update = 1;
 		topts.merge = 1;
 		topts.gently = opts->merge;
diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index 0706c95818..38fef34d3f 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -206,7 +206,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 			break;
 		case 2:
 			opts.fn = twoway_merge;
-			opts.initial_checkout = !active_nr;
+			opts.initial_checkout = is_cache_unborn();
 			break;
 		case 3:
 		default:
diff --git a/cache.h b/cache.h
index a1e4982cd4..3960931a95 100644
--- a/cache.h
+++ b/cache.h
@@ -255,6 +255,7 @@ static inline void remove_name_hash(struct cache_entry *ce)
 
 #define read_cache() read_index(&the_index)
 #define read_cache_from(path) read_index_from(&the_index, (path))
+#define is_cache_unborn() is_index_unborn(&the_index)
 #define read_cache_unmerged() read_index_unmerged(&the_index)
 #define write_cache(newfd, cache, entries) write_index(&the_index, (newfd))
 #define discard_cache() discard_index(&the_index)
@@ -360,6 +361,7 @@ extern int init_db(const char *template_dir, unsigned int flags);
 /* Initialize and use the cache information */
 extern int read_index(struct index_state *);
 extern int read_index_from(struct index_state *, const char *path);
+extern int is_index_unborn(struct index_state *);
 extern int read_index_unmerged(struct index_state *);
 extern int write_index(const struct index_state *, int newfd);
 extern int discard_index(struct index_state *);
diff --git a/read-cache.c b/read-cache.c
index 967f483f78..525d138e90 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1239,6 +1239,11 @@ unmap:
 	die("index file corrupt");
 }
 
+int is_index_unborn(struct index_state *istate)
+{
+	return (!istate->cache_nr && !istate->alloc && !istate->timestamp);
+}
+
 int discard_index(struct index_state *istate)
 {
 	istate->cache_nr = 0;