diff --git a/src/Back.cpp b/src/Back.cpp
index 7c0b8f34..c01a448a 100644
--- a/src/Back.cpp
+++ b/src/Back.cpp
@@ -1,5 +1,6 @@
 #include "Back.h"
 
+#include <stddef.h>
 #include <stdio.h>
 
 #include "WindowsWrapper.h"
diff --git a/src/Config.cpp b/src/Config.cpp
index e37b92a5..4c2d6d69 100644
--- a/src/Config.cpp
+++ b/src/Config.cpp
@@ -1,3 +1,4 @@
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
diff --git a/src/Draw.cpp b/src/Draw.cpp
index 5c7ce42a..4c30e934 100644
--- a/src/Draw.cpp
+++ b/src/Draw.cpp
@@ -1,5 +1,6 @@
 #include "Draw.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
diff --git a/src/Game.cpp b/src/Game.cpp
index b09ec22a..f4eaa39f 100644
--- a/src/Game.cpp
+++ b/src/Game.cpp
@@ -1,5 +1,6 @@
 #include "Game.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 
diff --git a/src/Input.cpp b/src/Input.cpp
index 7fa1a9b9..86905b6a 100644
--- a/src/Input.cpp
+++ b/src/Input.cpp
@@ -1,5 +1,6 @@
 #include "Input.h"
 
+#include <stddef.h>
 #include <stdio.h>
 
 #if defined(_MSC_VER) && _MSC_VER >= 1500	// Newer versions of Visual Studio don't support anything earlier than DirectInput8
diff --git a/src/Main.cpp b/src/Main.cpp
index d5939fd9..4332c64e 100644
--- a/src/Main.cpp
+++ b/src/Main.cpp
@@ -1,5 +1,6 @@
 #include "Main.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
diff --git a/src/Map.cpp b/src/Map.cpp
index 4b85a364..0657e620 100644
--- a/src/Map.cpp
+++ b/src/Map.cpp
@@ -1,5 +1,6 @@
 #include "Map.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/NpChar.cpp b/src/NpChar.cpp
index 06985e57..1c372892 100644
--- a/src/NpChar.cpp
+++ b/src/NpChar.cpp
@@ -1,5 +1,6 @@
 #include "NpChar.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
diff --git a/src/NpcTbl.cpp b/src/NpcTbl.cpp
index 34de4760..cf37082a 100644
--- a/src/NpcTbl.cpp
+++ b/src/NpcTbl.cpp
@@ -1,5 +1,6 @@
 #include "NpcTbl.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 
diff --git a/src/Organya.cpp b/src/Organya.cpp
index 43db6f2b..101f6b76 100644
--- a/src/Organya.cpp
+++ b/src/Organya.cpp
@@ -6,6 +6,7 @@
 
 #include "Organya.h"
 
+#include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
 
diff --git a/src/Profile.cpp b/src/Profile.cpp
index 7388d7fc..2b78a369 100644
--- a/src/Profile.cpp
+++ b/src/Profile.cpp
@@ -1,5 +1,6 @@
 #include "Profile.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <string.h>
 
diff --git a/src/Sound.cpp b/src/Sound.cpp
index 9a4e54aa..1ea8e196 100644
--- a/src/Sound.cpp
+++ b/src/Sound.cpp
@@ -12,6 +12,7 @@ equivalents.
 
 #include "Sound.h"
 
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>