diff --git a/runtime/src/zserio/Variant.h b/runtime/src/zserio/Variant.h
index bbe8c5e..89f7a70 100644
--- a/runtime/src/zserio/Variant.h
+++ b/runtime/src/zserio/Variant.h
@@ -513,11 +513,11 @@ class BasicVariant : public AllocatorHolder<ALLOC>
         }
         if constexpr (std::is_same_v<R, std::nullptr_t>)
         {
-            std::forward<F>(fun)(get<INDEX(I)>());
+            std::forward<F>(fun)(get<static_cast<INDEX>(I)>());
         }
         else
         {
-            returnValue = std::forward<F>(fun)(get<INDEX(I)>());
+            returnValue = std::forward<F>(fun)(get<static_cast<INDEX>(I)>());
         }
     }
 
@@ -530,11 +530,11 @@ class BasicVariant : public AllocatorHolder<ALLOC>
         }
         if constexpr (std::is_same_v<R, std::nullptr_t>)
         {
-            std::forward<F>(fun)(get<INDEX(I)>());
+            std::forward<F>(fun)(get<static_cast<INDEX>(I)>());
         }
         else
         {
-            returnValue = std::forward<F>(fun)(get<INDEX(I)>());
+            returnValue = std::forward<F>(fun)(get<static_cast<INDEX>(I)>());
         }
     }
 
@@ -551,7 +551,7 @@ class BasicVariant : public AllocatorHolder<ALLOC>
         {
             return true;
         }
-        return get<INDEX(I)>() == other.get<INDEX(I)>();
+        return get<static_cast<INDEX>(I)>() == other.get<static_cast<INDEX>(I)>();
     }
 
     template <size_t... I>
@@ -567,7 +567,7 @@ class BasicVariant : public AllocatorHolder<ALLOC>
         {
             return true;
         }
-        return get<INDEX(I)>() < other.get<INDEX(I)>();
+        return get<static_cast<INDEX>(I)>() < other.get<static_cast<INDEX>(I)>();
     }
 
     template <typename U, typename... ARGS>
@@ -624,7 +624,7 @@ class BasicVariant : public AllocatorHolder<ALLOC>
         {
             return;
         }
-        emplace<INDEX(I)>(other.get<INDEX(I)>());
+        emplace<static_cast<INDEX>(I)>(other.get<static_cast<INDEX>(I)>());
     }
 
     void move(BasicVariant&& other)
diff --git a/runtime/test/zserio/VariantTest.cpp b/runtime/test/zserio/VariantTest.cpp
index 79c72a4..820d52c 100644
--- a/runtime/test/zserio/VariantTest.cpp
+++ b/runtime/test/zserio/VariantTest.cpp
@@ -38,7 +38,7 @@ struct BigObj
     explicit BigObj(char obj) :
             data() // make clang-tidy happy
     {
-        data[0] = (char)obj;
+        data[0] = obj;
     }
     char value() const
     {