diff --git a/example/ex1/ex1.cpp b/example/ex1/ex1.cpp
index 8909e188..27de59ab 100644
--- a/example/ex1/ex1.cpp
+++ b/example/ex1/ex1.cpp
@@ -1,6 +1,6 @@
 /** @file ex1.cpp **/
 
-#include "xo/unit/quantity.hpp"
+#include "xo/unit/mpl/quantity.hpp"
 #include <iostream>
 
 int
diff --git a/example/ex2/ex2.cpp b/example/ex2/ex2.cpp
index 2caf4ee3..52b65a58 100644
--- a/example/ex2/ex2.cpp
+++ b/example/ex2/ex2.cpp
@@ -1,6 +1,6 @@
 /** @file ex2.cpp **/
 
-#include "xo/unit/quantity.hpp"
+#include "xo/unit/mpl/quantity.hpp"
 #include <iostream>
 
 int
diff --git a/example/ex3/ex3.cpp b/example/ex3/ex3.cpp
index 61a1d49c..623d2239 100644
--- a/example/ex3/ex3.cpp
+++ b/example/ex3/ex3.cpp
@@ -1,6 +1,6 @@
 /** @file ex3.cpp **/
 
-#include "xo/unit/quantity.hpp"
+#include "xo/unit/mpl/quantity.hpp"
 #include <iostream>
 
 int
diff --git a/example/ex4/ex4.cpp b/example/ex4/ex4.cpp
index 6db7f145..16c4aa03 100644
--- a/example/ex4/ex4.cpp
+++ b/example/ex4/ex4.cpp
@@ -1,6 +1,6 @@
 /** @file ex4.cpp **/
 
-#include "xo/unit/quantity.hpp"
+#include "xo/unit/mpl/quantity.hpp"
 #include <iostream>
 
 int
diff --git a/example/ex5/ex5.cpp b/example/ex5/ex5.cpp
index 2f0dbb9e..85dad01b 100644
--- a/example/ex5/ex5.cpp
+++ b/example/ex5/ex5.cpp
@@ -1,6 +1,6 @@
 /** @file ex5.cpp **/
 
-#include "xo/unit/quantity.hpp"
+#include "xo/unit/mpl/quantity.hpp"
 #include <iostream>
 
 int
diff --git a/example/ex6/ex6.cpp b/example/ex6/ex6.cpp
index 9046f331..a3e7b723 100644
--- a/example/ex6/ex6.cpp
+++ b/example/ex6/ex6.cpp
@@ -1,6 +1,6 @@
 /** @file ex6.cpp **/
 
-#include "xo/unit/quantity.hpp"
+#include "xo/unit/mpl/quantity.hpp"
 #include <iostream>
 
 int
diff --git a/include/xo/unit/quantity.hpp b/include/xo/unit/mpl/quantity.hpp
similarity index 100%
rename from include/xo/unit/quantity.hpp
rename to include/xo/unit/mpl/quantity.hpp
diff --git a/utest/quantity.test.cpp b/utest/quantity.test.cpp
index b2ade7c3..66d82a23 100644
--- a/utest/quantity.test.cpp
+++ b/utest/quantity.test.cpp
@@ -1,6 +1,6 @@
 /* @file quantity.test.cpp */
 
-#include "xo/unit/quantity.hpp"
+#include "xo/unit/mpl/quantity.hpp"
 #include "xo/reflect/Reflect.hpp"
 //#include <xo/randomgen/random_seed.hpp>
 //#include <xo/randomgen/xoshiro256.hpp>