diff --git a/builtin/fetch.c b/builtin/fetch.c
index 95fd0018b9..f142756441 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -1766,6 +1766,14 @@ static int do_fetch(struct transport *transport,
 					    branch->merge[i]->src);
 			}
 		}
+
+		/*
+		 * If there are no refs specified to fetch, then we just
+		 * fetch HEAD; mention that to narrow the advertisement.
+		 */
+		if (!transport_ls_refs_options.ref_prefixes.nr)
+			strvec_push(&transport_ls_refs_options.ref_prefixes,
+				    "HEAD");
 	}
 
 	if (tags == TAGS_SET || tags == TAGS_DEFAULT) {
diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index cea8f92a3d..2f0a52a72d 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -679,6 +679,21 @@ test_expect_success 'default refspec is used to filter ref when fetching' '
 	grep "ref-prefix refs/tags/" log
 '
 
+test_expect_success 'set up parent for prefix tests' '
+	git init prefix-parent &&
+	git -C prefix-parent commit --allow-empty -m foo &&
+	git -C prefix-parent branch unrelated-branch
+'
+
+test_expect_success 'empty refspec filters refs when fetching' '
+	git init configless-child &&
+
+	test_when_finished "rm -f log" &&
+	GIT_TRACE_PACKET="$(pwd)/log" \
+		git -C configless-child fetch ../prefix-parent &&
+	test_grep ! unrelated-branch log
+'
+
 test_expect_success 'fetch supports various ways of have lines' '
 	rm -rf server client trace &&
 	git init server &&