diff --git a/lib/ffi-geos.rb b/lib/ffi-geos.rb
index 2cd1397..9d1f162 100644
--- a/lib/ffi-geos.rb
+++ b/lib/ffi-geos.rb
@@ -1330,7 +1330,7 @@ def default_notice_handler(*args)
       end
 
       def default_error_handler(*args)
-        raise Geos::GEOSException, args[0] % args[1]
+        raise Geos::GEOSException, args[1] ? args[0] % args[1] : args[0]
       end
   end