diff --git a/Documentation/git-index-pack.txt b/Documentation/git-index-pack.txt
index 4be09e58e72145..58dd5b5f0e882f 100644
--- a/Documentation/git-index-pack.txt
+++ b/Documentation/git-index-pack.txt
@@ -144,6 +144,8 @@ Also, if there are objects in the given pack that references non-promisor
 objects (in the repo), repacks those non-promisor objects into a promisor
 pack. This avoids a situation in which a repo has non-promisor objects that are
 accessible through promisor objects.
++
+Requires <pack-file> to not be specified.
 
 NOTES
 -----
diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index d8f9360222e1fc..95babdc5ea7e72 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1970,6 +1970,8 @@ int cmd_index_pack(int argc,
 		usage(index_pack_usage);
 	if (fix_thin_pack && !from_stdin)
 		die(_("the option '%s' requires '%s'"), "--fix-thin", "--stdin");
+	if (promisor_msg && pack_name)
+		die(_("--promisor cannot be used with a pack name"));
 	if (from_stdin && !startup_info->have_repository)
 		die(_("--stdin requires a git repository"));
 	if (from_stdin && hash_algo)
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index aff164ddf8ec79..c53f355e48ced4 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -332,10 +332,8 @@ test_expect_success 'build pack index for an existing pack' '
 	git index-pack -o tmp.idx test-3.pack &&
 	cmp tmp.idx test-1-${packname_1}.idx &&
 
-	git index-pack --promisor=message test-3.pack &&
+	git index-pack test-3.pack &&
 	cmp test-3.idx test-1-${packname_1}.idx &&
-	echo message >expect &&
-	test_cmp expect test-3.promisor &&
 
 	cat test-2-${packname_2}.pack >test-3.pack &&
 	git index-pack -o tmp.idx test-2-${packname_2}.pack &&