1 files changed, 5 insertions, 3 deletions
diff --git a/src/include/open-axiom/token b/src/include/open-axiom/token
index a586fa6d..7f379593 100644
--- a/src/include/open-axiom/token
+++ b/src/include/open-axiom/token
@@ -483,13 +483,15 @@ namespace OpenAxiom {
             comment_token(t, TokenValue::Commentary);
             pos.column = frag(pos).length();
             break;
-         case '-':
-            if (pos.column + 1 < frag(pos).size()
-                and frag(pos)[pos.column + 1] == '>') {
+         case '-': {
+            std::size_t c = pos.column + 1;
+            if (c < frag(pos).size()
+                and frag(pos)[c] == '>') {
                t.value = TokenValue::MapsTo;
                pos.column += 2;
             }
             break;
+                   }
          default: break;
          }
    }