diff --git a/src/Main/fg_props.hxx b/src/Main/fg_props.hxx
index b20f10292..4025b185d 100644
--- a/src/Main/fg_props.hxx
+++ b/src/Main/fg_props.hxx
@@ -538,7 +538,7 @@ public:
         if (node->getType() != SGPropertyNode::STRING)
             return;
 
-        char *s = (char *)node->getStringValue();
+        char *s = const_cast<char *>(node->getStringValue());
         for (; *s; s++)
             *s = toupper(*s);
     }