diff --git a/include/teqp/models/CPA.hpp b/include/teqp/models/CPA.hpp
index 8427f5b3aed5251b6a2b3e8096e765ef686b2855..8fe74a98eede9e9d706d87ec7a7f114a3c1be7c6 100644
--- a/include/teqp/models/CPA.hpp
+++ b/include/teqp/models/CPA.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "nlohmann/json.hpp"
+
 namespace CPA {
 
 template<typename X> auto POW2(X x) { return x * x; };