diff --git a/builtin/merge-base.c b/builtin/merge-base.c
index daa96c790..87f4dbcca 100644
--- a/builtin/merge-base.c
+++ b/builtin/merge-base.c
@@ -73,7 +73,7 @@ static int handle_octopus(int count, const char **args, int show_all)
 	for (i = count - 1; i >= 0; i--)
 		commit_list_insert(get_commit_reference(args[i]), &revs);
 
-	result = get_octopus_merge_bases(revs);
+	result = reduce_heads(get_octopus_merge_bases(revs));
 
 	if (!result)
 		return 1;
diff --git a/t/t6010-merge-base.sh b/t/t6010-merge-base.sh
index f80bba871..abb5728b3 100755
--- a/t/t6010-merge-base.sh
+++ b/t/t6010-merge-base.sh
@@ -230,4 +230,43 @@ test_expect_success 'criss-cross merge-base for octopus-step' '
 	test_cmp expected.sorted actual.sorted
 '
 
+test_expect_success 'merge-base --octopus --all for complex tree' '
+	# Best common ancestor for JE, JAA and JDD is JC
+	#             JE
+	#            / |
+	#           /  |
+	#          /   |
+	#  JAA    /    |
+	#   |\   /     |
+	#   | \  | JDD |
+	#   |  \ |/ |  |
+	#   |   JC JD  |
+	#   |    | /|  |
+	#   |    |/ |  |
+	#  JA    |  |  |
+	#   |\  /|  |  |
+	#   X JB |  X  X
+	#   \  \ | /   /
+	#    \__\|/___/
+	#        J
+	test_commit J &&
+	test_commit JB &&
+	git reset --hard J &&
+	test_commit JC &&
+	git reset --hard J &&
+	test_commit JTEMP1 &&
+	test_merge JA JB &&
+	test_merge JAA JC &&
+	git reset --hard J &&
+	test_commit JTEMP2 &&
+	test_merge JD JB &&
+	test_merge JDD JC &&
+	git reset --hard J &&
+	test_commit JTEMP3 &&
+	test_merge JE JC &&
+	git rev-parse JC >expected &&
+	git merge-base --all --octopus JAA JDD JE >actual &&
+	test_cmp expected actual
+'
+
 test_done