diff --git a/tests/cpp/test_interpolation.cpp b/tests/cpp/test_interpolation.cpp
index a5df714849da53426cf33d053bab3a9117f1703a..c5b6fd067b90257ed4a3932588b57cf5b508dbd1 100644
--- a/tests/cpp/test_interpolation.cpp
+++ b/tests/cpp/test_interpolation.cpp
@@ -201,9 +201,9 @@ void test_performance() {
     // Generate random values
     std::random_device rd;
     std::mt19937 gen(rd());
-    constexpr double E_min = SS304L::E_neq.front() * 0.8;
-    constexpr double E_max = SS304L::E_neq.back() * 1.2;
-    std::uniform_real_distribution<double> dist(E_min, E_max);
+    constexpr double y_min = SS304L::y_neq.front() * 0.8;
+    constexpr double y_max = SS304L::y_neq.back() * 1.2;
+    std::uniform_real_distribution<double> dist(y_min, y_max);
 
     // Fill random energies
     for(auto& E : random_energies) {