diff --git a/components/esm/esmwriter.hpp b/components/esm/esmwriter.hpp
index 94f0a1004..33650e678 100644
--- a/components/esm/esmwriter.hpp
+++ b/components/esm/esmwriter.hpp
@@ -17,7 +17,7 @@ class ESMWriter
         {
             std::string name;
             std::streampos position;
-            size_t size;
+            uint32_t size;
         };
 
     public: