diff --git a/blame.c b/blame.c
index 686845b2b43dffe35d9f9811b61c80a0e0536332..de7b5d411fe3386661bea93388589977c67b3929 100644
--- a/blame.c
+++ b/blame.c
@@ -2670,7 +2670,7 @@ static struct commit *find_single_final(struct rev_info *revs,
 		if (obj->flags & UNINTERESTING)
 			continue;
 		obj = deref_tag(revs->repo, obj, NULL, 0);
-		if (obj->type != OBJ_COMMIT)
+		if (!obj || obj->type != OBJ_COMMIT)
 			die("Non commit %s?", revs->pending.objects[i].name);
 		if (found)
 			die("More than one commit to dig from %s and %s?",
@@ -2701,7 +2701,7 @@ static struct commit *dwim_reverse_initial(struct rev_info *revs,
 	/* Is that sole rev a committish? */
 	obj = revs->pending.objects[0].item;
 	obj = deref_tag(revs->repo, obj, NULL, 0);
-	if (obj->type != OBJ_COMMIT)
+	if (!obj || obj->type != OBJ_COMMIT)
 		return NULL;
 
 	/* Do we have HEAD? */
@@ -2737,7 +2737,7 @@ static struct commit *find_single_initial(struct rev_info *revs,
 		if (!(obj->flags & UNINTERESTING))
 			continue;
 		obj = deref_tag(revs->repo, obj, NULL, 0);
-		if (obj->type != OBJ_COMMIT)
+		if (!obj || obj->type != OBJ_COMMIT)
 			die("Non commit %s?", revs->pending.objects[i].name);
 		if (found)
 			die("More than one commit to dig up from, %s and %s?",
diff --git a/builtin/blame.c b/builtin/blame.c
index bb0f29300e5ca4caf3a6b9fa8e4ae96ce38c34d1..b5036ab3277ef10ab94d4b50df32f1251f788fe0 100644
--- a/builtin/blame.c
+++ b/builtin/blame.c
@@ -820,6 +820,8 @@ static int peel_to_commit_oid(struct object_id *oid_ret, void *cbdata)
 		if (kind != OBJ_TAG)
 			return -1;
 		obj = deref_tag(r, parse_object(r, &oid), NULL, 0);
+		if (!obj)
+			return -1;
 		oidcpy(&oid, &obj->oid);
 	}
 }
diff --git a/builtin/grep.c b/builtin/grep.c
index c8037388c6e7fd4c62d1a019b1c7b17f020370df..e58e57504c3b5108eb09c9d8198efaa4128ff363 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -670,6 +670,17 @@ static int grep_objects(struct grep_opt *opt, const struct pathspec *pathspec,
 				     NULL, 0);
 		obj_read_unlock();
 
+		if (!real_obj) {
+			char hex[GIT_MAX_HEXSZ + 1];
+			const char *name = list->objects[i].name;
+
+			if (!name) {
+				oid_to_hex_r(hex, &list->objects[i].item->oid);
+				name = hex;
+			}
+			die(_("invalid object '%s' given."), name);
+		}
+
 		/* load the gitmodules file for this rev */
 		if (recurse_submodules) {
 			submodule_free(opt->repo);
diff --git a/line-log.c b/line-log.c
index 68eeb425f8adff845409d2f0f7f64118d97593a2..75c8b1acfff86508614321a83989e2940fc21d4b 100644
--- a/line-log.c
+++ b/line-log.c
@@ -481,7 +481,7 @@ static struct commit *check_single_commit(struct rev_info *revs)
 		if (obj->flags & UNINTERESTING)
 			continue;
 		obj = deref_tag(revs->repo, obj, NULL, 0);
-		if (obj->type != OBJ_COMMIT)
+		if (!obj || obj->type != OBJ_COMMIT)
 			die("Non commit %s?", revs->pending.objects[i].name);
 		if (commit)
 			die("More than one commit to dig from: %s and %s?",