diff --git a/devtools/client/debugger/src/components/PrimaryPanes/tests/SourcesTree.spec.js b/devtools/client/debugger/src/components/PrimaryPanes/tests/SourcesTree.spec.js
index 0e98724997cf..15defca42e52 100644
--- a/devtools/client/debugger/src/components/PrimaryPanes/tests/SourcesTree.spec.js
+++ b/devtools/client/debugger/src/components/PrimaryPanes/tests/SourcesTree.spec.js
@@ -373,7 +373,7 @@ function generateDefaults(overrides: Object) {
       ),
       "server1.conn13.child1/42/originalSource-sha": createMockSource(
         "server1.conn13.child1/42/originalSource-sha",
-        "http://mdn.com/four.js",
+        "http://mdn.com/four.js [original]",
         false
       ),
       "server1.conn13.child1/42": createMockSource(
diff --git a/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap b/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap
index 2ad707e03340..4f3bf23418bf 100644
--- a/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap
+++ b/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap
@@ -179,11 +179,11 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
                   "isExtension": false,
                   "isPrettyPrinted": false,
                   "isWasm": false,
-                  "relativeUrl": "http://mdn.com/four.js",
-                  "url": "http://mdn.com/four.js",
+                  "relativeUrl": "http://mdn.com/four.js [original]",
+                  "url": "http://mdn.com/four.js [original]",
                 },
-                "name": "four.js",
-                "path": "FakeThread/mdn.com/four.js",
+                "name": "four.js%20[original]",
+                "path": "FakeThread/mdn.com/four.js%20[original]",
                 "type": "source",
               },
               Object {
@@ -273,11 +273,11 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
                       "isExtension": false,
                       "isPrettyPrinted": false,
                       "isWasm": false,
-                      "relativeUrl": "http://mdn.com/four.js",
-                      "url": "http://mdn.com/four.js",
+                      "relativeUrl": "http://mdn.com/four.js [original]",
+                      "url": "http://mdn.com/four.js [original]",
                     },
-                    "name": "four.js",
-                    "path": "FakeThread/mdn.com/four.js",
+                    "name": "four.js%20[original]",
+                    "path": "FakeThread/mdn.com/four.js%20[original]",
                     "type": "source",
                   },
                   Object {
diff --git a/devtools/client/debugger/src/utils/sources-tree/addToTree.js b/devtools/client/debugger/src/utils/sources-tree/addToTree.js
index 24ed990a0489..d08f57c777ca 100644
--- a/devtools/client/debugger/src/utils/sources-tree/addToTree.js
+++ b/devtools/client/debugger/src/utils/sources-tree/addToTree.js
@@ -36,10 +36,9 @@ function createNodeInTree(
 }
 
 /*
- * Look for the child directory
+ * Look for the child node
  * 1. if it exists return it
  * 2. if it does not exist create it
- * 3. if it is a file, replace it with a directory
  */
 function findOrCreateNode(
   parts: string[],
@@ -69,7 +68,7 @@ function findOrCreateNode(
   const childIsFile = !nodeHasChildren(child);
 
   // if we have a naming conflict, we'll create a new node
-  if (child.type === "source" || (!childIsFile && addedPartIsFile)) {
+  if (childIsFile != addedPartIsFile) {
     // pass true to findNodeInContents to sort node by url
     const { index: insertIndex } = findNodeInContents(
       subTree,
@@ -79,7 +78,7 @@ function findOrCreateNode(
   }
 
   // if there is no naming conflict, we can traverse into the child
-  return child;
+  return (child: any);
 }
 
 /*
@@ -132,7 +131,7 @@ function addSourceToNode(
 ): Source | TreeNode[] {
   const isFile = !isPathDirectory(url.path);
 
-  if (node.type == "source") {
+  if (node.type == "source" && !isFile) {
     throw new Error(`Unexpected type "source" at: ${node.name}`);
   }