diff --git a/code/Unreal/UnrealLoader.cpp b/code/Unreal/UnrealLoader.cpp
index 0bd4650d0..00b6b812d 100644
--- a/code/Unreal/UnrealLoader.cpp
+++ b/code/Unreal/UnrealLoader.cpp
@@ -403,7 +403,7 @@ void UnrealImporter::InternReadFile( const std::string& pFile,
 
         // set color and name
         mat->AddProperty(&color,1,AI_MATKEY_COLOR_DIFFUSE);
-        s.length = ::strlen(s.data);
+        s.length = (ai_uint32)::strlen(s.data);
         mat->AddProperty(&s,AI_MATKEY_NAME);
 
         // set texture, if any