diff --git a/tests/eos/eosTest.cpp b/tests/eos/eosTest.cpp
index b7a670b..a4c12ca 100644
--- a/tests/eos/eosTest.cpp
+++ b/tests/eos/eosTest.cpp
@@ -7,6 +7,8 @@
 #include "helm.h"
 #include "resourceManager.h"
 #include "config.h"
+#include "composition.h"
+#include "EOS.h"
 
 /**
  * @file constTest.cpp
@@ -39,7 +41,7 @@ TEST_F(eosTest, get_helm_EOS) {
 
     const int nel=3;
     double xmass[nel], aion[nel], zion[nel];
-    serif::eos::helmholtz::EOSInput eos1;
+    serif::eos::helmholtz::HELMEOSInput eos1;
 
     xmass[0] = 0.75; aion[0] =  1.0; zion[0] = 1.0;
     xmass[1] = 0.23; aion[1] =  4.0; zion[1] = 2.0; 
@@ -61,7 +63,7 @@ TEST_F(eosTest, get_helm_EOS) {
     auto& eos = std::get<std::unique_ptr<serif::eos::EOSio>>(rm.getResource("eos:helm"));
     auto& table = eos->getTable();
     auto& helmTable = *std::get<std::unique_ptr<serif::eos::helmholtz::HELMTable>>(table);
-    serif::eos::helmholtz::EOS helmEos = get_helm_EOS(eos1, helmTable);
+    serif::eos::helmholtz::HELMEOSOutput helmEos = get_helm_EOS(eos1, helmTable);
 
     const double absErr = 1e-12;
 
@@ -85,3 +87,25 @@ TEST_F(eosTest, get_helm_EOS) {
     EXPECT_NEAR(    helmEos.dpe,              0, absErr);
     EXPECT_NEAR(    helmEos.dsp,              0, absErr);
 }
+
+TEST_F(eosTest, eos_using_composition) {
+    serif::composition::Composition composition;
+    composition.registerSymbol({"H-1", "He-4", "C-12"}, true);
+    composition.setMassFraction("H-1", 0.75);
+    composition.setMassFraction("He-4", 0.23);
+    composition.setMassFraction("C-12", 0.02);
+    composition.finalize();
+
+    serif::resource::ResourceManager& rm = serif::resource::ResourceManager::getInstance();
+    auto& EOSio = std::get<std::unique_ptr<serif::eos::EOSio>>(rm.getResource("eos:helm"));
+
+    serif::eos::EOS EOS(*EOSio);
+
+    serif::eos::EOSInput eosInput;
+    eosInput.temperature = 1.0e8; // Temperature in K
+    eosInput.density = 1.0e6; // Density in g/cm^3
+    eosInput.composition = composition; // Set the composition
+
+    serif::eos::EOSOutput eosOutput;
+    EXPECT_NO_THROW(eosOutput = EOS.get(eosInput));
+}
diff --git a/tests/eos/meson.build b/tests/eos/meson.build
index d8154e6..61b86e3 100644
--- a/tests/eos/meson.build
+++ b/tests/eos/meson.build
@@ -3,6 +3,16 @@ test_sources = [
     'eosTest.cpp',
 ]
 
+dependencies = [
+    gtest_dep,
+    eos_dep,
+    gtest_main,
+    resourceManager_dep,
+    config_dep,
+    composition_dep,
+]
+
+
 foreach test_file : test_sources
   exe_name = test_file.split('.')[0]
   message('Building test: ' + exe_name)
@@ -11,7 +21,7 @@ foreach test_file : test_sources
   test_exe = executable(
       exe_name,
       test_file,
-      dependencies: [gtest_dep, eos_dep, gtest_main, resourceManager_dep, config_dep],
+      dependencies: dependencies,
       install_rpath: '@loader_path/../../src'  # Ensure runtime library path resolves correctly
   )
 
diff --git a/tests/resource/resourceManagerTest.cpp b/tests/resource/resourceManagerTest.cpp
index 2936653..4238689 100644
--- a/tests/resource/resourceManagerTest.cpp
+++ b/tests/resource/resourceManagerTest.cpp
@@ -48,7 +48,7 @@ TEST_F(resourceManagerTest, getResource) {
     const serif::resource::types::Resource &r = rm.getResource(name);
     // BREAKPOINT();
     const auto &eos = std::get<std::unique_ptr<serif::eos::EOSio>>(r);
-    EXPECT_EQ("helm", eos->getFormat());
+    EXPECT_EQ("Helmholtz", eos->getFormatName());
     serif::eos::EOSTable &table = eos->getTable();
 
     // -- Extract the Helm table from the EOSTable