diff --git a/include/aabb.h b/include/aabb.h
index e693a40..79f15de 100644
--- a/include/aabb.h
+++ b/include/aabb.h
@@ -34,6 +34,7 @@
 #pragma once
 
 #include <functional> // for hash<>
+#include <type_traits>
 
 #include "vector2.h"
 #include "vector3.h"
diff --git a/include/hitinfo.h b/include/hitinfo.h
index 0d9749b..8f5204d 100644
--- a/include/hitinfo.h
+++ b/include/hitinfo.h
@@ -32,6 +32,7 @@
 #pragma once
 
 #include "vector3.h"
+#include <type_traits>
 
 class KRNode;
 
diff --git a/include/matrix2.h b/include/matrix2.h
index ad41ea9..72769c0 100644
--- a/include/matrix2.h
+++ b/include/matrix2.h
@@ -28,10 +28,10 @@
 //  authors and should not be interpreted as representing official policies, either expressed
 //  or implied, of Kearwood Gilbert.
 //
+#pragma once
 
 #include "vector2.h"
-
-#pragma once
+#include <type_traits>
 
 namespace hydra {
 
diff --git a/include/matrix2x3.h b/include/matrix2x3.h
index 3599404..a13db89 100644
--- a/include/matrix2x3.h
+++ b/include/matrix2x3.h
@@ -29,10 +29,11 @@
 //  or implied, of Kearwood Gilbert.
 //
 
+#pragma once
+
 #include "vector2.h"
 #include "vector3.h"
-
-#pragma once
+#include <type_traits>
 
 namespace hydra {
 
diff --git a/include/matrix4.h b/include/matrix4.h
index f7d3e12..9b24ea5 100644
--- a/include/matrix4.h
+++ b/include/matrix4.h
@@ -29,11 +29,11 @@
 //  or implied, of Kearwood Gilbert.
 //
 
+#pragma once
 
 #include "vector3.h"
 #include "vector4.h"
-
-#pragma once
+#include <type_traits>
 
 namespace hydra {
 
diff --git a/include/quaternion.h b/include/quaternion.h
index be2aff5..d54e9bb 100644
--- a/include/quaternion.h
+++ b/include/quaternion.h
@@ -32,6 +32,7 @@
 #pragma once
 
 #include "vector3.h"
+#include <type_traits>
 
 namespace hydra {
 
diff --git a/include/triangle3.h b/include/triangle3.h
index 6c66fe0..c925451 100644
--- a/include/triangle3.h
+++ b/include/triangle3.h
@@ -32,6 +32,7 @@
 #pragma once
 
 #include "vector3.h"
+#include <type_traits>
 
 namespace hydra {
 
diff --git a/include/vector2.h b/include/vector2.h
index ff25496..fe04e2e 100644
--- a/include/vector2.h
+++ b/include/vector2.h
@@ -34,6 +34,7 @@
 #include <functional> // for hash<>
 #include <limits> // for std::numeric_limits<>
 #include <math.h> // for sqrtf
+#include <type_traits>
 
 namespace hydra {
 
diff --git a/include/vector2i.h b/include/vector2i.h
index 2a63a5c..8bf0d01 100644
--- a/include/vector2i.h
+++ b/include/vector2i.h
@@ -34,6 +34,7 @@
 #include <functional> // for hash<>
 #include <limits> // for std::numeric_limits<>
 #include <math.h> // for sqrtf
+#include <type_traits>
 
 namespace hydra {
 
diff --git a/include/vector3.h b/include/vector3.h
index c9b5a2b..7367f71 100644
--- a/include/vector3.h
+++ b/include/vector3.h
@@ -32,6 +32,7 @@
 #pragma once
 
 #include <functional> // for hash<>
+#include <type_traits>
 
 #include "vector2.h"
 #include "vector4.h"
diff --git a/include/vector3i.h b/include/vector3i.h
index e9c7d6b..19d16df 100644
--- a/include/vector3i.h
+++ b/include/vector3i.h
@@ -32,6 +32,7 @@
 #pragma once
 
 #include <functional> // for hash<>
+#include <type_traits>
 
 #include "vector2i.h"
 
diff --git a/include/vector4.h b/include/vector4.h
index 31b0c61..beb597b 100644
--- a/include/vector4.h
+++ b/include/vector4.h
@@ -32,6 +32,7 @@
 #pragma once
 
 #include <functional> // for hash<>
+#include <type_traits>
 
 namespace hydra {