diff --git a/src/m_cheat.cpp b/src/m_cheat.cpp
index c8256dda4..6fd1ef6a6 100644
--- a/src/m_cheat.cpp
+++ b/src/m_cheat.cpp
@@ -49,6 +49,7 @@
 #include "a_keys.h"
 #include "d_net.h"
 #include "serializer.h"
+#include "serialize_obj.h"
 #include "r_utility.h"
 #include "a_morph.h"
 #include "g_levellocals.h"
diff --git a/src/playsim/bots/b_bot.cpp b/src/playsim/bots/b_bot.cpp
index 1f628a88e..97eb37829 100644
--- a/src/playsim/bots/b_bot.cpp
+++ b/src/playsim/bots/b_bot.cpp
@@ -46,6 +46,7 @@
 #include "teaminfo.h"
 #include "d_net.h"
 #include "serializer_doom.h"
+#include "serialize_obj.h"
 #include "d_player.h"
 #include "filesystem.h"
 #include "vm.h"
diff --git a/src/playsim/p_acs.cpp b/src/playsim/p_acs.cpp
index bbefd5ad5..f29105ed0 100644
--- a/src/playsim/p_acs.cpp
+++ b/src/playsim/p_acs.cpp
@@ -63,6 +63,7 @@
 #include "po_man.h"
 #include "actorptrselect.h"
 #include "serializer_doom.h"
+#include "serialize_obj.h"
 #include "decallib.h"
 #include "p_terrain.h"
 #include "version.h"
diff --git a/src/playsim/p_mobj.cpp b/src/playsim/p_mobj.cpp
index c4898686f..097a7f7be 100644
--- a/src/playsim/p_mobj.cpp
+++ b/src/playsim/p_mobj.cpp
@@ -89,6 +89,7 @@
 #include "p_spec.h"
 #include "p_checkposition.h"
 #include "serializer_doom.h"
+#include "serialize_obj.h"
 #include "r_utility.h"
 #include "thingdef.h"
 #include "d_player.h"