diff --git a/apps/openmw_test_suite/serialization/format.hpp b/apps/openmw_test_suite/serialization/format.hpp
index 8f61838fde..603d2790e0 100644
--- a/apps/openmw_test_suite/serialization/format.hpp
+++ b/apps/openmw_test_suite/serialization/format.hpp
@@ -5,6 +5,7 @@
 
 #include <utility>
 #include <type_traits>
+#include <cstdint>
 
 namespace SerializationTesting
 {
@@ -20,7 +21,7 @@ namespace SerializationTesting
         }
     };
 
-    enum Enum
+    enum Enum : std::int32_t
     {
         A,
         B,
@@ -30,7 +31,7 @@ namespace SerializationTesting
     struct Composite
     {
         short mFloatArray[3] = {0};
-        std::vector<int> mIntVector;
+        std::vector<std::int32_t> mIntVector;
         std::vector<Enum> mEnumVector;
         std::vector<Pod> mPodVector;
         std::size_t mPodDataSize = 0;
diff --git a/components/serialization/format.hpp b/components/serialization/format.hpp
index 595afd0dad..956345149c 100644
--- a/components/serialization/format.hpp
+++ b/components/serialization/format.hpp
@@ -7,6 +7,7 @@
 #include <type_traits>
 #include <utility>
 #include <vector>
+#include <cstdint>
 
 namespace Serialization
 {
@@ -51,13 +52,13 @@ namespace Serialization
             -> std::enable_if_t<isContiguousContainer<T>>
         {
             if constexpr (mode == Mode::Write)
-                visitor(self(), value.size());
+                visitor(self(), static_cast<std::uint64_t>(value.size()));
             else
             {
                 static_assert(mode == Mode::Read);
-                std::size_t size = 0;
+                std::uint64_t size = 0;
                 visitor(self(), size);
-                value.resize(size);
+                value.resize(static_cast<std::size_t>(size));
             }
             self()(std::forward<Visitor>(visitor), value.data(), value.size());
         }