diff --git a/src/composition/private/composition.cpp b/src/composition/private/composition.cpp
index aad84dc..25ddbdf 100644
--- a/src/composition/private/composition.cpp
+++ b/src/composition/private/composition.cpp
@@ -357,7 +357,7 @@ namespace serif::composition {
             for (const auto& mass_fraction : mass_fractions) {
                 sum += mass_fraction;
             }
-            for (int i = 0; i < mass_fractions.size(); ++i) {
+            for (int i = 0; i < static_cast<int>(mass_fractions.size()); ++i) {
                 mass_fractions[i] /= sum;
             }
             for (auto& [symbol, entry] : m_compositions) {
@@ -594,10 +594,10 @@ namespace serif::composition {
             throw std::runtime_error("Composition has not been finalized (Consider running .finalize()).");
         }
         CanonicalComposition canonicalComposition;
-        constexpr std::array<std::string, 7> canonicalH = {
+        const std::array<std::string, 7> canonicalH = {
             "H-1", "H-2", "H-3", "H-4", "H-5", "H-6", "H-7"
         };
-        constexpr std::array<std::string, 8> canonicalHe = {
+        const std::array<std::string, 8> canonicalHe = {
             "He-3", "He-4", "He-5", "He-6", "He-7", "He-8", "He-9", "He-10"
         };
         for (const auto& symbol : canonicalH) {
diff --git a/tests/composition/compositionTest.cpp b/tests/composition/compositionTest.cpp
index 7553162..7a99133 100644
--- a/tests/composition/compositionTest.cpp
+++ b/tests/composition/compositionTest.cpp
@@ -61,13 +61,13 @@ TEST_F(compositionTest, setGetComposition) {
     EXPECT_THROW(comp.setMassFraction("He-3", 0.3), std::runtime_error);
 
     EXPECT_NO_THROW(comp.setMassFraction({"H-1", "He-4"}, {0.5, 0.5}));
-    EXPECT_THROW(comp.getComposition("H-1"), std::runtime_error);
+    EXPECT_THROW(auto r = comp.getComposition("H-1"), std::runtime_error);
     EXPECT_TRUE(comp.finalize());
     EXPECT_DOUBLE_EQ(comp.getComposition("H-1").first.mass_fraction(), 0.5);
 
     EXPECT_NO_THROW(comp.setMassFraction({"H-1", "He-4"}, {0.6, 0.6}));
     EXPECT_FALSE(comp.finalize());
-    EXPECT_THROW(comp.getComposition("H-1"), std::runtime_error);
+    EXPECT_THROW(auto r = comp.getComposition("H-1"), std::runtime_error);
 }
 
 TEST_F(compositionTest, setGetNumberFraction) {