diff --git a/src/systems/include/mp-units/systems/hep/hep.h b/src/systems/include/mp-units/systems/hep/hep.h
index ac7a192e8..637fc27fc 100644
--- a/src/systems/include/mp-units/systems/hep/hep.h
+++ b/src/systems/include/mp-units/systems/hep/hep.h
@@ -22,8 +22,7 @@
 
 #pragma once
 
-#include <mp-units/systems/si/constants.h>
-#include <mp-units/systems/si/units.h>
+#include <mp-units/systems/si/si.h>
 #include <mp-units/unit.h>
 
 template<>
@@ -53,6 +52,8 @@ inline constexpr struct speed_of_light : decltype(si::si2019::speed_of_light_in_
 
 namespace unit_symbols {
 
+using si::unit_symbols::eV;
+
 inline constexpr auto qeV = si::quecto<electronvolt>;
 inline constexpr auto reV = si::ronto<electronvolt>;
 inline constexpr auto yeV = si::yocto<electronvolt>;
@@ -65,7 +66,6 @@ inline constexpr auto ueV = si::micro<electronvolt>;
 inline constexpr auto meV = si::milli<electronvolt>;
 inline constexpr auto ceV = si::centi<electronvolt>;
 inline constexpr auto deV = si::deci<electronvolt>;
-inline constexpr auto eV = electronvolt;
 inline constexpr auto daeV = si::deca<electronvolt>;
 inline constexpr auto heV = si::hecto<electronvolt>;
 inline constexpr auto keV = si::kilo<electronvolt>;
diff --git a/test/static/iau_test.cpp b/test/static/iau_test.cpp
index 547385380..32ccf3c8b 100644
--- a/test/static/iau_test.cpp
+++ b/test/static/iau_test.cpp
@@ -25,7 +25,8 @@ import mp_units;
 #else
 #include <mp-units/math.h>
 #include <mp-units/systems/iau/iau.h>
-#include <mp-units/systems/si/unit_symbols.h>
+#include <mp-units/systems/isq/space_and_time.h>
+#include <mp-units/systems/si/si.h>
 #endif
 
 /* ************** DERIVED DIMENSIONS THAT INCLUDE UNITS WITH SPECIAL NAMES **************** */