diff --git a/collects/tests/racket/htdp.rktl b/collects/tests/racket/htdp.rktl
index b7da6b8202..00ff6cf4f6 100644
--- a/collects/tests/racket/htdp.rktl
+++ b/collects/tests/racket/htdp.rktl
@@ -1,10 +1,10 @@
 
 (load-relative "loadtest.rktl")
 
-(load-in-sandbox "beginner.ss")
-(load-in-sandbox "beginner-abbr.ss")
-(load-in-sandbox "intermediate.ss")
-(load-in-sandbox "intermediate-lambda.ss")
-(load-in-sandbox "advanced.ss")
+(load-in-sandbox "beginner.rktl")
+(load-in-sandbox "beginner-abbr.rktl")
+(load-in-sandbox "intermediate.rktl")
+(load-in-sandbox "intermediate-lambda.rktl")
+(load-in-sandbox "advanced.rktl")
 
 (report-errs)