diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index de00adbb9e..df49f656b9 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -3311,9 +3311,26 @@ static void read_packs_list_from_stdin(void)
 	}
 
 	/*
-	 * First handle all of the excluded packs, marking them as kept in-core
-	 * so that later calls to add_object_entry() discards any objects that
-	 * are also found in excluded packs.
+	 * Arguments we got on stdin may not even be packs. First
+	 * check that to avoid segfaulting later on in
+	 * e.g. pack_mtime_cmp(), excluded packs are handled below.
+	 *
+	 * Since we first parsed our STDIN and then sorted the input
+	 * lines the pack we error on will be whatever line happens to
+	 * sort first. This is lazy, it's enough that we report one
+	 * bad case here, we don't need to report the first/last one,
+	 * or all of them.
+	 */
+	for_each_string_list_item(item, &include_packs) {
+		struct packed_git *p = item->util;
+		if (!p)
+			die(_("could not find pack '%s'"), item->string);
+	}
+
+	/*
+	 * Then, handle all of the excluded packs, marking them as
+	 * kept in-core so that later calls to add_object_entry()
+	 * discards any objects that are also found in excluded packs.
 	 */
 	for_each_string_list_item(item, &exclude_packs) {
 		struct packed_git *p = item->util;
diff --git a/t/t5300-pack-object.sh b/t/t5300-pack-object.sh
index 65e991e370..e13a884207 100755
--- a/t/t5300-pack-object.sh
+++ b/t/t5300-pack-object.sh
@@ -119,6 +119,25 @@ test_expect_success 'pack-object <stdin parsing: [|--revs] with --stdin' '
 	test_cmp err.expect err.actual
 '
 
+test_expect_success 'pack-object <stdin parsing: --stdin-packs handles garbage' '
+	cat >in <<-EOF &&
+	$(git -C pack-object-stdin rev-parse one)
+	$(git -C pack-object-stdin rev-parse two)
+	EOF
+
+	# That we get "two" and not "one" has to do with OID
+	# ordering. It happens to be the same here under SHA-1 and
+	# SHA-256. See commentary in pack-objects.c
+	cat >err.expect <<-EOF &&
+	fatal: could not find pack '"'"'$(git -C pack-object-stdin rev-parse two)'"'"'
+	EOF
+	test_must_fail git \
+		-C pack-object-stdin \
+		pack-objects stdin-with-stdin-option --stdin-packs \
+		<in 2>err.actual &&
+	test_cmp err.expect err.actual
+'
+
 # usage: check_deltas <stderr_from_pack_objects> <cmp_op> <nr_deltas>
 # e.g.: check_deltas stderr -gt 0
 check_deltas() {