diff --git a/reachable.c b/reachable.c
index c62efbfd43b9c4ddc25d6768d55bddc745f5c14b..492e87b9fa00c392ef799567dc6ef60e2dfb18a5 100644
--- a/reachable.c
+++ b/reachable.c
@@ -9,6 +9,7 @@
 #include "cache-tree.h"
 #include "progress.h"
 #include "list-objects.h"
+#include "worktree.h"
 
 struct connectivity_progress {
 	struct progress *progress;
@@ -176,6 +177,7 @@ void mark_reachable_objects(struct rev_info *revs, int mark_reflog,
 
 	/* detached HEAD is not included in the list above */
 	head_ref(add_one_ref, revs);
+	other_head_refs(add_one_ref, revs);
 
 	/* Add all reflog info */
 	if (mark_reflog)
diff --git a/revision.c b/revision.c
index 8d045162661a81e779b18e1295d470f4194d2f50..0e9844485720ecd77b0e46bac242f691019b0bef 100644
--- a/revision.c
+++ b/revision.c
@@ -2133,6 +2133,14 @@ static int handle_revision_pseudo_opt(const char *submodule,
 	int argcount;
 
 	if (submodule) {
+		/*
+		 * We need some something like get_submodule_worktrees()
+		 * before we can go through all worktrees of a submodule,
+		 * .e.g with adding all HEADs from --all, which is not
+		 * supported right now, so stick to single worktree.
+		 */
+		if (!revs->single_worktree)
+			die("BUG: --single-worktree cannot be used together with submodule");
 		refs = get_submodule_ref_store(submodule);
 	} else
 		refs = get_main_ref_store();
@@ -2150,6 +2158,12 @@ static int handle_revision_pseudo_opt(const char *submodule,
 	if (!strcmp(arg, "--all")) {
 		handle_refs(refs, revs, *flags, refs_for_each_ref);
 		handle_refs(refs, revs, *flags, refs_head_ref);
+		if (!revs->single_worktree) {
+			struct all_refs_cb cb;
+
+			init_all_refs_cb(&cb, revs, *flags);
+			other_head_refs(handle_one_ref, &cb);
+		}
 		clear_ref_exclusion(&revs->ref_excludes);
 	} else if (!strcmp(arg, "--branches")) {
 		handle_refs(refs, revs, *flags, refs_for_each_branch_ref);
diff --git a/submodule.c b/submodule.c
index 98e1f9d3c7b61bb14527fb67b82cb5aa0ebe4ead..61a38adcd477205c1d8edd0aae0d2e89248e9cd3 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1685,6 +1685,8 @@ static int find_first_merges(struct object_array *result, const char *path,
 			oid_to_hex(&a->object.oid));
 	init_revisions(&revs, NULL);
 	rev_opts.submodule = path;
+	/* FIXME: can't handle linked worktrees in submodules yet */
+	revs.single_worktree = path != NULL;
 	setup_revisions(ARRAY_SIZE(rev_args)-1, rev_args, &revs, &rev_opts);
 
 	/* save all revisions from the above list that contain b */
diff --git a/t/t5304-prune.sh b/t/t5304-prune.sh
index cba45c7be91279f11a5ad603e9c21b334d7cb615..683bdb031c7d7913b6e4e69e20c9faecf2bc1bbc 100755
--- a/t/t5304-prune.sh
+++ b/t/t5304-prune.sh
@@ -292,4 +292,16 @@ test_expect_success 'prune: handle index in multiple worktrees' '
 	test_cmp second-worktree/blob actual
 '
 
+test_expect_success 'prune: handle HEAD in multiple worktrees' '
+	git worktree add --detach third-worktree &&
+	echo "new blob for third-worktree" >third-worktree/blob &&
+	git -C third-worktree add blob &&
+	git -C third-worktree commit -m "third" &&
+	rm .git/worktrees/third-worktree/index &&
+	test_must_fail git -C third-worktree show :blob &&
+	git prune --expire=now &&
+	git -C third-worktree show HEAD:blob >actual &&
+	test_cmp third-worktree/blob actual
+'
+
 test_done
diff --git a/worktree.c b/worktree.c
index e28ffbeb096a85d67b2e885c48ab096340b5d295..389e2e952cb92fbf1f42b717310ed186fc704eb5 100644
--- a/worktree.c
+++ b/worktree.c
@@ -386,3 +386,25 @@ int submodule_uses_worktrees(const char *path)
 	closedir(dir);
 	return ret;
 }
+
+int other_head_refs(each_ref_fn fn, void *cb_data)
+{
+	struct worktree **worktrees, **p;
+	int ret = 0;
+
+	worktrees = get_worktrees(0);
+	for (p = worktrees; *p; p++) {
+		struct worktree *wt = *p;
+		struct ref_store *refs;
+
+		if (wt->is_current)
+			continue;
+
+		refs = get_worktree_ref_store(wt);
+		ret = refs_head_ref(refs, fn, cb_data);
+		if (ret)
+			break;
+	}
+	free_worktrees(worktrees);
+	return ret;
+}
diff --git a/worktree.h b/worktree.h
index 5ea5e503fbe491a76d3c8ce279b7e281a5d07d3e..9276c81ae7cb5c42a86fd9ebbdb28720be409e47 100644
--- a/worktree.h
+++ b/worktree.h
@@ -1,6 +1,8 @@
 #ifndef WORKTREE_H
 #define WORKTREE_H
 
+#include "refs.h"
+
 struct worktree {
 	char *path;
 	char *id;
@@ -70,6 +72,12 @@ extern void free_worktrees(struct worktree **);
 extern const struct worktree *find_shared_symref(const char *symref,
 						 const char *target);
 
+/*
+ * Similar to head_ref() for all HEADs _except_ one from the current
+ * worktree, which is covered by head_ref().
+ */
+int other_head_refs(each_ref_fn fn, void *cb_data);
+
 int is_worktree_being_rebased(const struct worktree *wt, const char *target);
 int is_worktree_being_bisected(const struct worktree *wt, const char *target);