diff --git a/src/eval.js b/src/eval.js
index f8999e0..39bf3f0 100644
--- a/src/eval.js
+++ b/src/eval.js
@@ -18,7 +18,7 @@ import {has_toplevel_await} from './find_definitions.js'
 
 // import runtime as external because it has non-functional code
 // external
-import {run, do_eval_expand_calltree_node, Multiversion} from './runtime.js'
+import {run, do_eval_expand_calltree_node, Multiversion} from './runtime/runtime.js'
 
 // TODO: fix error messages. For example, "__fn is not a function"
 
diff --git a/src/record_io.js b/src/runtime/record_io.js
similarity index 100%
rename from src/record_io.js
rename to src/runtime/record_io.js
diff --git a/src/runtime.js b/src/runtime/runtime.js
similarity index 100%
rename from src/runtime.js
rename to src/runtime/runtime.js