diff --git a/Derivs/src/derivs_spacetimex.hxx b/Derivs/src/derivs_spacetimex.hxx
index 6a51e6e5a..9823cf219 100644
--- a/Derivs/src/derivs_spacetimex.hxx
+++ b/Derivs/src/derivs_spacetimex.hxx
@@ -1,5 +1,5 @@
-#ifndef CARPETX_DERIVS_DERIVS_HXX
-#define CARPETX_DERIVS_DERIVS_HXX
+#ifndef CARPETX_DERIVS_SPACETIMEX_DERIVS_HXX
+#define CARPETX_DERIVS_SPACETIMEX_DERIVS_HXX
 
 #include <loop_device.hxx>
 #include <mat.hxx>
@@ -13,6 +13,8 @@
 #include <type_traits>
 // Unified derivative header
 
+namespace derivs_spacetimex {
+
 // TODO: Make this a runtime parameter
 constexpr int deriv_order = 4;
 
@@ -508,5 +510,7 @@ void CCTK_ATTRIBUTE_NOINLINE calc_copy(const cGH *restrict const cctkGH,
     for (int b = a; b < 3; ++b)
       calc_copy(cctkGH, gf0_(a, b), gf_(a, b), layout);
 }
+ 
+}
 
 #endif // #ifndef CARPETX_DERIVS_DERIVS_HXX