diff --git a/src/com/google/javascript/jscomp/Es6RewriteModules.java b/src/com/google/javascript/jscomp/Es6RewriteModules.java
index e70cd611eda..800da6a3a62 100644
--- a/src/com/google/javascript/jscomp/Es6RewriteModules.java
+++ b/src/com/google/javascript/jscomp/Es6RewriteModules.java
@@ -174,7 +174,13 @@ public void hotSwapScript(Node scriptNode, Node originalRoot) {
     if (isEs6ModuleRoot(scriptNode)) {
       processFile(scriptNode);
     } else {
-      NodeTraversal.traverse(compiler, scriptNode, new RewriteRequiresForEs6Modules());
+      RewriteRequiresForEs6Modules rewriter = new RewriteRequiresForEs6Modules();
+
+      NodeTraversal.traverse(compiler, scriptNode, rewriter);
+
+      if (rewriter.transpiled) {
+        scriptNode.putBooleanProp(Node.TRANSPILED, true);
+      }
     }
   }
 
@@ -184,6 +190,7 @@ public void hotSwapScript(Node scriptNode, Node originalRoot) {
   private void processFile(Node root) {
     checkArgument(isEs6ModuleRoot(root), root);
     clearState();
+    root.putBooleanProp(Node.TRANSPILED, true);
     NodeTraversal.traverse(compiler, root, this);
   }
 
@@ -201,6 +208,8 @@ public void clearState() {
    * modules and rewrites them.
    */
   private class RewriteRequiresForEs6Modules extends AbstractPostOrderCallback {
+    boolean transpiled = false;
+
     @Override
     public void visit(NodeTraversal t, Node n, Node parent) {
       if (n.isCall()) {
@@ -251,6 +260,8 @@ public void visit(NodeTraversal t, Node n, Node parent) {
             n.detach();
             t.reportCodeChange();
           }
+
+          transpiled = true;
         }
       }
     }
diff --git a/src/com/google/javascript/jscomp/Es6RewriteModulesToCommonJsModules.java b/src/com/google/javascript/jscomp/Es6RewriteModulesToCommonJsModules.java
index 54897d18097..0a50c6fdd15 100644
--- a/src/com/google/javascript/jscomp/Es6RewriteModulesToCommonJsModules.java
+++ b/src/com/google/javascript/jscomp/Es6RewriteModulesToCommonJsModules.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
 import com.google.javascript.jscomp.deps.ModuleLoader.ModulePath;
+import com.google.javascript.jscomp.parsing.parser.FeatureSet.Feature;
 import com.google.javascript.rhino.IR;
 import com.google.javascript.rhino.Node;
 import com.google.javascript.rhino.Token;
@@ -60,8 +61,10 @@ public void process(Node externs, Node root) {
     for (Node script : root.children()) {
       if (Es6RewriteModules.isEs6ModuleRoot(script)) {
         NodeTraversal.traverse(compiler, script, new Rewriter(compiler, script));
+        script.putBooleanProp(Node.TRANSPILED, true);
       }
     }
+    compiler.setFeatureSet(compiler.getFeatureSet().without(Feature.MODULES));
   }
 
   private static class LocalQName {