diff --git a/object-name.c b/object-name.c
index f0e327f91f..2dc5d2549b 100644
--- a/object-name.c
+++ b/object-name.c
@@ -1881,6 +1881,20 @@ static char *resolve_relative_path(struct repository *r, const char *rel)
 			   rel);
 }
 
+static int reject_tree_in_index(struct repository *repo,
+				int only_to_die,
+				const struct cache_entry *ce,
+				int stage,
+				const char *prefix,
+				const char *cp)
+{
+	if (!S_ISSPARSEDIR(ce->ce_mode))
+		return 0;
+	if (only_to_die)
+		diagnose_invalid_index_path(repo, stage, prefix, cp);
+	return -1;
+}
+
 static enum get_oid_result get_oid_with_context_1(struct repository *repo,
 				  const char *name,
 				  unsigned flags,
@@ -1955,9 +1969,12 @@ static enum get_oid_result get_oid_with_context_1(struct repository *repo,
 			    memcmp(ce->name, cp, namelen))
 				break;
 			if (ce_stage(ce) == stage) {
+				free(new_path);
+				if (reject_tree_in_index(repo, only_to_die, ce,
+							 stage, prefix, cp))
+					return -1;
 				oidcpy(oid, &ce->oid);
 				oc->mode = ce->ce_mode;
-				free(new_path);
 				return 0;
 			}
 			pos++;
diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
index 3506c0216f..08c9cfd359 100755
--- a/t/t1092-sparse-checkout-compatibility.sh
+++ b/t/t1092-sparse-checkout-compatibility.sh
@@ -1165,15 +1165,8 @@ test_expect_success 'show (cached blobs/trees)' '
 	test_must_fail git -C full-checkout show :folder1/ &&
 	test_must_fail git -C sparse-checkout show :folder1/ &&
 
-	git -C sparse-index show :folder1/ >actual &&
-	git -C full-checkout show HEAD:folder1 >expect &&
-
-	# The output of "git show" includes the way we referenced the
-	# objects, so strip that out.
-	test_line_count = 4 actual &&
-	tail -n 2 actual >actual-trunc &&
-	tail -n 2 expect >expect-trunc &&
-	test_cmp expect-trunc actual-trunc
+	test_must_fail git -C sparse-index show :folder1/ 2>err &&
+	grep "is in the index, but not at stage 0" err
 '
 
 test_expect_success 'submodule handling' '