diff --git a/src/history.cpp b/src/history.cpp
index 868c97557..5c6e24bc5 100644
--- a/src/history.cpp
+++ b/src/history.cpp
@@ -238,7 +238,7 @@ struct history_impl_t {
     // item_at_index until a call to resolve_pending(). Pending items are tracked with an offset
     // into the array of new items, so adding a non-pending item has the effect of resolving all
     // pending items.
-    void add(history_item_t item, bool pending = false, bool do_save = true);
+    void add(history_item_t &&item, bool pending = false, bool do_save = true);
 
     // Internal function.
     void clear_file_state();
@@ -379,7 +379,7 @@ struct history_impl_t {
     size_t size();
 };
 
-void history_impl_t::add(history_item_t item, bool pending, bool do_save) {
+void history_impl_t::add(history_item_t &&item, bool pending, bool do_save) {
     assert(item.timestamp() != 0 && "Should not add an item with a 0 timestamp");
     // We use empty items as sentinels to indicate the end of history.
     // Do not allow them to be added (#6032).
@@ -1096,7 +1096,7 @@ bool history_impl_t::is_empty() {
 
 void history_t::add(wcstring str) {
     auto imp = this->impl();
-    time_t when =  imp->timestamp_now();
+    time_t when = imp->timestamp_now();
     imp->add(history_item_t(std::move(str), when));
 }
 
@@ -1327,7 +1327,7 @@ bool history_t::is_default() const { return impl()->is_default(); }
 
 bool history_t::is_empty() { return impl()->is_empty(); }
 
-void history_t::add(history_item_t item, bool pending) { impl()->add(std::move(item), pending); }
+void history_t::add(history_item_t &&item, bool pending) { impl()->add(std::move(item), pending); }
 
 void history_t::remove(const wcstring &str) { impl()->remove(str); }
 
diff --git a/src/history.h b/src/history.h
index daa22f037..8b8dc4bb8 100644
--- a/src/history.h
+++ b/src/history.h
@@ -146,7 +146,7 @@ class history_t {
 
     // Privately add an item. If pending, the item will not be returned by history searches until a
     // call to resolve_pending. Any trailing ephemeral items are dropped.
-    void add(history_item_t item, bool pending = false);
+    void add(history_item_t &&item, bool pending = false);
 
     // Add a new history item with text \p str to the end of history.
     void add(wcstring str);
diff --git a/src/timer.cpp b/src/timer.cpp
index 0291311f2..699844a61 100644
--- a/src/timer.cpp
+++ b/src/timer.cpp
@@ -71,7 +71,7 @@ timer_snapshot_t timer_snapshot_t::take() {
     return snapshot;
 }
 
-wcstring timer_snapshot_t::print_delta(timer_snapshot_t t1, timer_snapshot_t t2,
+wcstring timer_snapshot_t::print_delta(const timer_snapshot_t &t1, const timer_snapshot_t &t2,
                                        bool verbose /* = true */) {
     int64_t fish_sys_micros = micros(t2.cpu_fish.ru_stime) - micros(t1.cpu_fish.ru_stime);
     int64_t fish_usr_micros = micros(t2.cpu_fish.ru_utime) - micros(t1.cpu_fish.ru_utime);
diff --git a/src/timer.h b/src/timer.h
index 997e98c11..e43ead5d4 100644
--- a/src/timer.h
+++ b/src/timer.h
@@ -22,7 +22,8 @@ struct timer_snapshot_t {
     std::chrono::time_point<std::chrono::steady_clock> wall;
 
     static timer_snapshot_t take();
-    static wcstring print_delta(timer_snapshot_t t1, timer_snapshot_t t2, bool verbose = false);
+    static wcstring print_delta(const timer_snapshot_t &t1, const timer_snapshot_t &t2,
+                                bool verbose = false);
 
    private:
     timer_snapshot_t() {}