diff --git a/include/InputFunctions/sourceTerm.h b/include/InputFunctions/sourceTerm.h
index 2903e24e..8f01321d 100644
--- a/include/InputFunctions/sourceTerm.h
+++ b/include/InputFunctions/sourceTerm.h
@@ -1,5 +1,8 @@
 #pragma once
 
+#include <concepts>
+#include <cstddef>
+
 namespace concepts
 {