diff --git a/Source/DiabloUI/credits.cpp b/Source/DiabloUI/credits.cpp
index 17c343a32e8..41b765b0e84 100644
--- a/Source/DiabloUI/credits.cpp
+++ b/Source/DiabloUI/credits.cpp
@@ -14,6 +14,7 @@
 #include "engine/render/text_render.hpp"
 #include "hwcursor.hpp"
 #include "utils/display.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 #include "utils/sdl_compat.h"
diff --git a/Source/DiabloUI/diabloui.cpp b/Source/DiabloUI/diabloui.cpp
index 680d1b3ca21..c1289f7b560 100644
--- a/Source/DiabloUI/diabloui.cpp
+++ b/Source/DiabloUI/diabloui.cpp
@@ -24,6 +24,7 @@
 #include "hwcursor.hpp"
 #include "utils/algorithm/container.hpp"
 #include "utils/display.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 #include "utils/pcx_to_clx.hpp"
diff --git a/Source/DiabloUI/dialogs.cpp b/Source/DiabloUI/dialogs.cpp
index 8b125b76be0..4b60e8a27af 100644
--- a/Source/DiabloUI/dialogs.cpp
+++ b/Source/DiabloUI/dialogs.cpp
@@ -16,6 +16,7 @@
 #include "engine/palette.h"
 #include "hwcursor.hpp"
 #include "utils/display.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 
diff --git a/Source/DiabloUI/progress.cpp b/Source/DiabloUI/progress.cpp
index bc627e38e24..2a15b61b2eb 100644
--- a/Source/DiabloUI/progress.cpp
+++ b/Source/DiabloUI/progress.cpp
@@ -12,6 +12,7 @@
 #include "engine/render/clx_render.hpp"
 #include "hwcursor.hpp"
 #include "utils/display.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 
 namespace devilution {
diff --git a/Source/DiabloUI/settingsmenu.cpp b/Source/DiabloUI/settingsmenu.cpp
index 3e6be08b1a5..37ae4142656 100644
--- a/Source/DiabloUI/settingsmenu.cpp
+++ b/Source/DiabloUI/settingsmenu.cpp
@@ -14,6 +14,7 @@
 #include "engine/render/text_render.hpp"
 #include "hwcursor.hpp"
 #include "options.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/utf8.hpp"
 
diff --git a/Source/automap.cpp b/Source/automap.cpp
index 491a7846abf..23a6c93a670 100644
--- a/Source/automap.cpp
+++ b/Source/automap.cpp
@@ -19,6 +19,7 @@
 #include "player.h"
 #include "utils/attributes.h"
 #include "utils/enum_traits.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/ui_fwd.h"
 #include "utils/utf8.hpp"
diff --git a/Source/automap.h b/Source/automap.h
index dee4cd2736b..e12d752ed4c 100644
--- a/Source/automap.h
+++ b/Source/automap.h
@@ -7,9 +7,9 @@
 
 #include <cstdint>
 
-#include "engine.h"
 #include "engine/displacement.hpp"
 #include "engine/point.hpp"
+#include "engine/surface.hpp"
 #include "levels/gendung.h"
 #include "utils/attributes.h"
 
diff --git a/Source/controls/controller_motion.cpp b/Source/controls/controller_motion.cpp
index 23363413c0b..568a04f7493 100644
--- a/Source/controls/controller_motion.cpp
+++ b/Source/controls/controller_motion.cpp
@@ -13,6 +13,7 @@
 #include "controls/touch/gamepad.h"
 #include "engine/demomode.h"
 #include "options.h"
+#include "utils/is_of.hpp"
 #include "utils/log.hpp"
 
 namespace devilution {
diff --git a/Source/controls/game_controls.cpp b/Source/controls/game_controls.cpp
index 9c6cfd3bb56..58e74f709a3 100644
--- a/Source/controls/game_controls.cpp
+++ b/Source/controls/game_controls.cpp
@@ -16,6 +16,7 @@
 #include "panels/spell_list.hpp"
 #include "qol/stash.h"
 #include "stores.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/controls/plrctrls.cpp b/Source/controls/plrctrls.cpp
index 01bdbf50a3b..9045df2bc88 100644
--- a/Source/controls/plrctrls.cpp
+++ b/Source/controls/plrctrls.cpp
@@ -38,6 +38,7 @@
 #include "stores.h"
 #include "towners.h"
 #include "track.h"
+#include "utils/is_of.hpp"
 #include "utils/log.hpp"
 #include "utils/str_cat.hpp"
 
diff --git a/Source/controls/touch/event_handlers.cpp b/Source/controls/touch/event_handlers.cpp
index 5e2b3906790..e5ecbb82677 100644
--- a/Source/controls/touch/event_handlers.cpp
+++ b/Source/controls/touch/event_handlers.cpp
@@ -12,6 +12,7 @@
 #include "panels/spell_list.hpp"
 #include "qol/stash.h"
 #include "stores.h"
+#include "utils/is_of.hpp"
 #include "utils/ui_fwd.h"
 
 namespace devilution {
diff --git a/Source/cursor.cpp b/Source/cursor.cpp
index 08f8ae84590..54174b1209c 100644
--- a/Source/cursor.cpp
+++ b/Source/cursor.cpp
@@ -34,6 +34,7 @@
 #include "towners.h"
 #include "track.h"
 #include "utils/attributes.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/sdl_bilinear_scale.hpp"
 #include "utils/surface_to_clx.hpp"
diff --git a/Source/data/file.hpp b/Source/data/file.hpp
index 39a759cf0f5..4bbad2689a1 100644
--- a/Source/data/file.hpp
+++ b/Source/data/file.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstddef>
+#include <limits>
 #include <memory>
 #include <string_view>
 
diff --git a/Source/data/parser.hpp b/Source/data/parser.hpp
index 90ce4d9ef6e..b6fd6230670 100644
--- a/Source/data/parser.hpp
+++ b/Source/data/parser.hpp
@@ -3,7 +3,7 @@
 #include <algorithm>
 #include <string_view>
 
-#include "engine.h" // For IsAnyOf
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/diablo.cpp b/Source/diablo.cpp
index 8937e9cc836..0d55ce46673 100644
--- a/Source/diablo.cpp
+++ b/Source/diablo.cpp
@@ -86,6 +86,7 @@
 #include "track.h"
 #include "utils/console.h"
 #include "utils/display.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/parse_int.hpp"
 #include "utils/paths.h"
diff --git a/Source/dvlnet/base_protocol.h b/Source/dvlnet/base_protocol.h
index c296da00b6d..6e4f205c831 100644
--- a/Source/dvlnet/base_protocol.h
+++ b/Source/dvlnet/base_protocol.h
@@ -11,6 +11,7 @@
 #include "dvlnet/packet.h"
 #include "player.h"
 #include "utils/algorithm/container.hpp"
+#include "utils/is_of.hpp"
 #include "utils/log.hpp"
 
 namespace devilution::net {
diff --git a/Source/effects.cpp b/Source/effects.cpp
index 1df897a0916..24cadcd75e1 100644
--- a/Source/effects.cpp
+++ b/Source/effects.cpp
@@ -19,6 +19,7 @@
 #include "engine/sound_position.hpp"
 #include "init.h"
 #include "player.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/engine.h b/Source/engine.h
index a1ce99bf2d4..1ed3cd7aed7 100644
--- a/Source/engine.h
+++ b/Source/engine.h
@@ -40,18 +40,6 @@
 
 namespace devilution {
 
-template <typename V, typename X, typename... Xs>
-DVL_ALWAYS_INLINE constexpr bool IsAnyOf(const V &v, X x, Xs... xs)
-{
-	return v == x || ((v == xs) || ...);
-}
-
-template <typename V, typename X, typename... Xs>
-DVL_ALWAYS_INLINE constexpr bool IsNoneOf(const V &v, X x, Xs... xs)
-{
-	return v != x && ((v != xs) && ...);
-}
-
 /**
  * @brief Fill a rectangle with the given color.
  */
diff --git a/Source/engine/demomode.cpp b/Source/engine/demomode.cpp
index ca9d34ab62d..c0c337b4472 100644
--- a/Source/engine/demomode.cpp
+++ b/Source/engine/demomode.cpp
@@ -21,6 +21,7 @@
 #include "utils/console.h"
 #include "utils/display.h"
 #include "utils/endian_stream.hpp"
+#include "utils/is_of.hpp"
 #include "utils/paths.h"
 #include "utils/str_cat.hpp"
 
diff --git a/Source/engine/displacement.hpp b/Source/engine/displacement.hpp
index 4056335dcbe..341838b562e 100644
--- a/Source/engine/displacement.hpp
+++ b/Source/engine/displacement.hpp
@@ -1,6 +1,8 @@
 #pragma once
 
 #include <cmath>
+#include <limits>
+
 #ifdef BUILD_TESTING
 #include <ostream>
 #endif
diff --git a/Source/engine/events.cpp b/Source/engine/events.cpp
index 7bf6051485b..ae791d6651a 100644
--- a/Source/engine/events.cpp
+++ b/Source/engine/events.cpp
@@ -9,6 +9,7 @@
 #include "movie.h"
 #include "options.h"
 #include "panels/console.hpp"
+#include "utils/is_of.hpp"
 #include "utils/log.hpp"
 
 #ifdef USE_SDL1
diff --git a/Source/engine/render/scrollrt.cpp b/Source/engine/render/scrollrt.cpp
index 0e656c13888..d160b269aab 100644
--- a/Source/engine/render/scrollrt.cpp
+++ b/Source/engine/render/scrollrt.cpp
@@ -54,6 +54,7 @@
 #include "towners.h"
 #include "utils/attributes.h"
 #include "utils/display.h"
+#include "utils/is_of.hpp"
 #include "utils/log.hpp"
 #include "utils/str_cat.hpp"
 
diff --git a/Source/engine/render/text_render.cpp b/Source/engine/render/text_render.cpp
index a248945af12..da2e5d0ce9f 100644
--- a/Source/engine/render/text_render.cpp
+++ b/Source/engine/render/text_render.cpp
@@ -27,6 +27,7 @@
 #include "engine/render/clx_render.hpp"
 #include "utils/algorithm/container.hpp"
 #include "utils/display.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/sdl_compat.h"
 #include "utils/utf8.hpp"
diff --git a/Source/inv.cpp b/Source/inv.cpp
index 6a88617c86a..8d20a13d127 100644
--- a/Source/inv.cpp
+++ b/Source/inv.cpp
@@ -33,6 +33,7 @@
 #include "stores.h"
 #include "towners.h"
 #include "utils/format_int.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/sdl_geometry.h"
 #include "utils/str_cat.hpp"
diff --git a/Source/items.cpp b/Source/items.cpp
index 80fb9c98fbf..f05dbf25e85 100644
--- a/Source/items.cpp
+++ b/Source/items.cpp
@@ -41,6 +41,7 @@
 #include "spells.h"
 #include "stores.h"
 #include "utils/format_int.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 #include "utils/math.h"
diff --git a/Source/items.h b/Source/items.h
index 1bb0805f4f5..db4528e1f6d 100644
--- a/Source/items.h
+++ b/Source/items.h
@@ -15,6 +15,7 @@
 #include "engine/point.hpp"
 #include "itemdat.h"
 #include "monster.h"
+#include "utils/is_of.hpp"
 #include "utils/string_or_view.hpp"
 
 namespace devilution {
diff --git a/Source/items/validation.cpp b/Source/items/validation.cpp
index b5d71a95fe9..608be7bd7b0 100644
--- a/Source/items/validation.cpp
+++ b/Source/items/validation.cpp
@@ -12,6 +12,7 @@
 #include "monstdat.h"
 #include "player.h"
 #include "spells.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/levels/drlg_l1.cpp b/Source/levels/drlg_l1.cpp
index 564153ded20..bffa03ee3a5 100644
--- a/Source/levels/drlg_l1.cpp
+++ b/Source/levels/drlg_l1.cpp
@@ -11,6 +11,7 @@
 #include "player.h"
 #include "quests.h"
 #include "utils/bitset2d.hpp"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/levels/drlg_l2.cpp b/Source/levels/drlg_l2.cpp
index b01f9659337..1e83c202b8a 100644
--- a/Source/levels/drlg_l2.cpp
+++ b/Source/levels/drlg_l2.cpp
@@ -19,6 +19,7 @@
 #include "levels/setmaps.h"
 #include "player.h"
 #include "quests.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/levels/drlg_l3.cpp b/Source/levels/drlg_l3.cpp
index cf64377f1b4..9d729f27056 100644
--- a/Source/levels/drlg_l3.cpp
+++ b/Source/levels/drlg_l3.cpp
@@ -14,6 +14,7 @@
 #include "objects.h"
 #include "player.h"
 #include "quests.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/levels/drlg_l4.cpp b/Source/levels/drlg_l4.cpp
index d7260aa1c58..8e2737d3610 100644
--- a/Source/levels/drlg_l4.cpp
+++ b/Source/levels/drlg_l4.cpp
@@ -14,6 +14,7 @@
 #include "multi.h"
 #include "objdat.h"
 #include "player.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/levels/gendung.cpp b/Source/levels/gendung.cpp
index f625f7bd9dd..03d8e331082 100644
--- a/Source/levels/gendung.cpp
+++ b/Source/levels/gendung.cpp
@@ -25,6 +25,7 @@
 #include "lighting.h"
 #include "options.h"
 #include "utils/bitset2d.hpp"
+#include "utils/is_of.hpp"
 #include "utils/log.hpp"
 #include "utils/status_macros.hpp"
 
diff --git a/Source/levels/themes.cpp b/Source/levels/themes.cpp
index f3be95d005c..2c266dd16f3 100644
--- a/Source/levels/themes.cpp
+++ b/Source/levels/themes.cpp
@@ -18,6 +18,7 @@
 #include "objects.h"
 #include "quests.h"
 #include "utils/algorithm/container.hpp"
+#include "utils/is_of.hpp"
 #include "utils/str_cat.hpp"
 
 namespace devilution {
diff --git a/Source/levels/trigs.cpp b/Source/levels/trigs.cpp
index e91f90b1c17..3b1374dc37f 100644
--- a/Source/levels/trigs.cpp
+++ b/Source/levels/trigs.cpp
@@ -16,6 +16,7 @@
 #include "diablo_msg.hpp"
 #include "init.h"
 #include "utils/algorithm/container.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/utf8.hpp"
 
diff --git a/Source/lighting.cpp b/Source/lighting.cpp
index 32429c46855..e09b1e3d97e 100644
--- a/Source/lighting.cpp
+++ b/Source/lighting.cpp
@@ -18,6 +18,7 @@
 #include "engine/points_in_rectangle_range.hpp"
 #include "player.h"
 #include "utils/attributes.h"
+#include "utils/is_of.hpp"
 #include "utils/status_macros.hpp"
 
 namespace devilution {
diff --git a/Source/loadsave.cpp b/Source/loadsave.cpp
index ad0dc45c4b2..fe508a34813 100644
--- a/Source/loadsave.cpp
+++ b/Source/loadsave.cpp
@@ -38,6 +38,7 @@
 #include "stores.h"
 #include "utils/algorithm/container.hpp"
 #include "utils/endian.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/status_macros.hpp"
 
diff --git a/Source/lua/modules/dev/items.cpp b/Source/lua/modules/dev/items.cpp
index bc4871e6ec3..ca329ee31bd 100644
--- a/Source/lua/modules/dev/items.cpp
+++ b/Source/lua/modules/dev/items.cpp
@@ -12,6 +12,7 @@
 #include "lua/metadoc.hpp"
 #include "pack.h"
 #include "player.h"
+#include "utils/is_of.hpp"
 #include "utils/str_case.hpp"
 #include "utils/str_cat.hpp"
 
diff --git a/Source/lua/modules/dev/quests.cpp b/Source/lua/modules/dev/quests.cpp
index a3329e82d86..138bd00f195 100644
--- a/Source/lua/modules/dev/quests.cpp
+++ b/Source/lua/modules/dev/quests.cpp
@@ -9,6 +9,7 @@
 #include "engine.h"
 #include "lua/metadoc.hpp"
 #include "quests.h"
+#include "utils/is_of.hpp"
 #include "utils/str_cat.hpp"
 
 namespace devilution {
diff --git a/Source/missiles.cpp b/Source/missiles.cpp
index f2cd1a15832..7fb7d99b8bc 100644
--- a/Source/missiles.cpp
+++ b/Source/missiles.cpp
@@ -27,6 +27,7 @@
 #include "lighting.h"
 #include "monster.h"
 #include "spells.h"
+#include "utils/is_of.hpp"
 #include "utils/str_cat.hpp"
 
 namespace devilution {
diff --git a/Source/missiles.h b/Source/missiles.h
index f78d6d64cc0..0411633b0bf 100644
--- a/Source/missiles.h
+++ b/Source/missiles.h
@@ -16,6 +16,7 @@
 #include "monster.h"
 #include "player.h"
 #include "spelldat.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/monster.cpp b/Source/monster.cpp
index 34b734394f6..892f8fa2157 100644
--- a/Source/monster.cpp
+++ b/Source/monster.cpp
@@ -47,6 +47,7 @@
 #include "utils/attributes.h"
 #include "utils/cl2_to_clx.hpp"
 #include "utils/file_name_generator.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 #include "utils/static_vector.hpp"
diff --git a/Source/msg.cpp b/Source/msg.cpp
index cbcfd6bcb31..2c655de82ee 100644
--- a/Source/msg.cpp
+++ b/Source/msg.cpp
@@ -42,6 +42,7 @@
 #include "sync.h"
 #include "tmsg.h"
 #include "towners.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/str_cat.hpp"
 #include "utils/utf8.hpp"
diff --git a/Source/multi.cpp b/Source/multi.cpp
index c5d75334262..1530360c58e 100644
--- a/Source/multi.cpp
+++ b/Source/multi.cpp
@@ -29,6 +29,7 @@
 #include "sync.h"
 #include "tmsg.h"
 #include "utils/endian.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/str_cat.hpp"
 
diff --git a/Source/objects.cpp b/Source/objects.cpp
index a326d2539c9..edbf690ddf5 100644
--- a/Source/objects.cpp
+++ b/Source/objects.cpp
@@ -44,6 +44,7 @@
 #include "towners.h"
 #include "track.h"
 #include "utils/algorithm/container.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 #include "utils/str_cat.hpp"
diff --git a/Source/objects.h b/Source/objects.h
index 576787d15c2..7cafbaa9ebe 100644
--- a/Source/objects.h
+++ b/Source/objects.h
@@ -21,6 +21,7 @@
 #include "objdat.h"
 #include "textdat.h"
 #include "utils/attributes.h"
+#include "utils/is_of.hpp"
 #include "utils/string_or_view.hpp"
 
 namespace devilution {
diff --git a/Source/options.cpp b/Source/options.cpp
index c1a095e07fa..d6fcfd4657b 100644
--- a/Source/options.cpp
+++ b/Source/options.cpp
@@ -30,6 +30,7 @@
 #include "utils/display.h"
 #include "utils/file_util.h"
 #include "utils/ini.hpp"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 #include "utils/logged_fstream.hpp"
diff --git a/Source/pack.cpp b/Source/pack.cpp
index ead5c464d87..6f0970edf30 100644
--- a/Source/pack.cpp
+++ b/Source/pack.cpp
@@ -15,6 +15,7 @@
 #include "plrmsg.h"
 #include "stores.h"
 #include "utils/endian.hpp"
+#include "utils/is_of.hpp"
 #include "utils/log.hpp"
 #include "utils/utf8.hpp"
 
diff --git a/Source/player.cpp b/Source/player.cpp
index f4b144127f0..4e771bc59dd 100644
--- a/Source/player.cpp
+++ b/Source/player.cpp
@@ -43,6 +43,7 @@
 #include "spells.h"
 #include "stores.h"
 #include "towners.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/log.hpp"
 #include "utils/str_cat.hpp"
diff --git a/Source/player.h b/Source/player.h
index c703a0fec24..73860095ef3 100644
--- a/Source/player.h
+++ b/Source/player.h
@@ -27,6 +27,7 @@
 #include "spelldat.h"
 #include "utils/attributes.h"
 #include "utils/enum_traits.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/quests.cpp b/Source/quests.cpp
index 984bdc8a5de..ecf573f32f6 100644
--- a/Source/quests.cpp
+++ b/Source/quests.cpp
@@ -28,6 +28,7 @@
 #include "panels/ui_panels.hpp"
 #include "stores.h"
 #include "towners.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/utf8.hpp"
 
diff --git a/Source/sync.cpp b/Source/sync.cpp
index d758212d667..abd510ffceb 100644
--- a/Source/sync.cpp
+++ b/Source/sync.cpp
@@ -11,6 +11,7 @@
 #include "lighting.h"
 #include "monster.h"
 #include "player.h"
+#include "utils/is_of.hpp"
 
 namespace devilution {
 
diff --git a/Source/towners.cpp b/Source/towners.cpp
index b89786a185e..0894c5be5f4 100644
--- a/Source/towners.cpp
+++ b/Source/towners.cpp
@@ -10,6 +10,7 @@
 #include "inv.h"
 #include "minitext.h"
 #include "stores.h"
+#include "utils/is_of.hpp"
 #include "utils/language.h"
 #include "utils/str_case.hpp"
 
diff --git a/Source/utils/is_of.hpp b/Source/utils/is_of.hpp
new file mode 100644
index 00000000000..fff5f6c37a8
--- /dev/null
+++ b/Source/utils/is_of.hpp
@@ -0,0 +1,19 @@
+#pragma once
+
+#include "utils/attributes.h"
+
+namespace devilution {
+
+template <typename V, typename X, typename... Xs>
+DVL_ALWAYS_INLINE constexpr bool IsAnyOf(const V &v, X x, Xs... xs)
+{
+	return v == x || ((v == xs) || ...);
+}
+
+template <typename V, typename X, typename... Xs>
+DVL_ALWAYS_INLINE constexpr bool IsNoneOf(const V &v, X x, Xs... xs)
+{
+	return v != x && ((v != xs) && ...);
+}
+
+} // namespace devilution
diff --git a/test/pack_test.cpp b/test/pack_test.cpp
index d72d0f5cc6f..9a436ea098a 100644
--- a/test/pack_test.cpp
+++ b/test/pack_test.cpp
@@ -6,6 +6,7 @@
 #include "monstdat.h"
 #include "pack.h"
 #include "playerdat.hpp"
+#include "utils/is_of.hpp"
 #include "utils/paths.h"
 
 namespace devilution {