diff --git a/code/PlyLoader.cpp b/code/PlyLoader.cpp
index 15e20b2c4..4e6ea8137 100644
--- a/code/PlyLoader.cpp
+++ b/code/PlyLoader.cpp
@@ -123,7 +123,9 @@ const aiImporterDesc* PLYImporter::GetInfo () const
 }
 
 // ------------------------------------------------------------------------------------------------
-static bool isBigEndian( char* szMe ) {
+static bool isBigEndian( const char* szMe ) {
+    ai_assert( NULL != szMe );
+
     // binary_little_endian
     // binary_big_endian
     bool isBigEndian( false );