diff --git a/corsika/detail/modules/radio/CoREAS.inl b/corsika/detail/modules/radio/CoREAS.inl
index 317d3febfcbb42cba6b5cca73f8e9c0c396e43e1..2d5a75cf00bd3280cb9bb06dba20a99a317c9866 100644
--- a/corsika/detail/modules/radio/CoREAS.inl
+++ b/corsika/detail/modules/radio/CoREAS.inl
@@ -50,8 +50,7 @@ namespace corsika {
       auto const thinningWeight{step.getParticlePre().getWeight()};
 
       // constants for electric field vector calculation
-      auto const constants_{(charge_ / (4 * M_PI) / (constants::epsilonZero) /
-                            constants::c) * thinningWeight};
+      auto const constants_{charge_ * emConstant_ * thinningWeight};
 
       // set threshold for application of ZHS-like approximation.
       const double approxThreshold_{1.0e-3};
diff --git a/corsika/detail/modules/radio/ZHS.inl b/corsika/detail/modules/radio/ZHS.inl
index db6971c5f21c00f60b3c0a598092e27d63461cd1..28d45f0ffb486048f53a066b855489ff11362988 100644
--- a/corsika/detail/modules/radio/ZHS.inl
+++ b/corsika/detail/modules/radio/ZHS.inl
@@ -44,7 +44,7 @@ namespace corsika {
       // get thinning weight
       auto const thinningWeight{step.getParticlePre().getWeight()};
 
-      auto const constants{(charge / (4 * M_PI) / (constants::epsilonZero) / constants::c) * thinningWeight};
+      auto const constants{charge * emConstant_ * thinningWeight};
 
       // we loop over each antenna in the collection
       for (auto& antenna : antennas_.getAntennas()) {
diff --git a/corsika/modules/radio/CoREAS.hpp b/corsika/modules/radio/CoREAS.hpp
index 058126aa7fb3070d2dac8e3c6de26989ad211e75..dc2f81d5c419791400f5e65d6d4b0fb4572fe04b 100644
--- a/corsika/modules/radio/CoREAS.hpp
+++ b/corsika/modules/radio/CoREAS.hpp
@@ -47,6 +47,8 @@ namespace corsika {
      */
     template <typename Particle>
     ProcessReturn simulate(Step<Particle> const& step);
+    static constexpr auto emConstant_{1.0 / (4.0 * M_PI) / (constants::epsilonZero) /
+                                      constants::c};
 
     using Base =
         RadioProcess<TRadioDetector, CoREAS<TRadioDetector, TPropagator>, TPropagator>;
diff --git a/corsika/modules/radio/ZHS.hpp b/corsika/modules/radio/ZHS.hpp
index 49153ba25c5ac2707e5c58adfc98153928846c26..6da01f888aa9ea0229ca1a9fd42d208317af658a 100644
--- a/corsika/modules/radio/ZHS.hpp
+++ b/corsika/modules/radio/ZHS.hpp
@@ -49,6 +49,8 @@ namespace corsika {
      */
     template <typename Particle>
     ProcessReturn simulate(Step<Particle> const& step) const;
+    static constexpr auto emConstant_{1.0 / (4.0 * M_PI) / (constants::epsilonZero) /
+                                      constants::c};
 
   private:
     using Base =