diff --git a/scripts/fiber/tests-passing-except-dev.txt b/scripts/fiber/tests-passing-except-dev.txt
index bd22db6cba..95cad08849 100644
--- a/scripts/fiber/tests-passing-except-dev.txt
+++ b/scripts/fiber/tests-passing-except-dev.txt
@@ -1,61 +1,3 @@
-src/renderers/__tests__/ReactComponentTreeHook-test.js
-* uses displayName or Unknown for classic components
-* uses displayName, name, or ReactComponent for modern components
-* uses displayName, name, or Object for factory components
-* uses displayName, name, or StatelessComponent for functional components
-* reports a host tree correctly
-* reports a simple tree with composites correctly
-* reports a tree with composites correctly
-* ignores null children
-* ignores false children
-* reports text nodes as children
-* reports a single text node as a child
-* reports a single number node as a child
-* reports a zero as a child
-* skips empty nodes for multiple children
-* reports html content as no children
-* updates text of a single text child
-* updates from no children to a single text child
-* updates from a single text child to no children
-* updates from html content to a single text child
-* updates from a single text child to html content
-* updates from no children to multiple text children
-* updates from multiple text children to no children
-* updates from html content to multiple text children
-* updates from multiple text children to html content
-* updates from html content to no children
-* updates from no children to html content
-* updates from one text child to multiple text children
-* updates from multiple text children to one text child
-* updates text nodes when reordering
-* updates host nodes when reordering with keys
-* updates host nodes when reordering without keys
-* updates a single composite child of a different type
-* updates a single composite child of the same type
-* updates from no children to a single composite child
-* updates from a single composite child to no children
-* updates mixed children
-* updates with a host child
-* updates from null to a host child
-* updates from a host child to null
-* updates from a host child to a composite child
-* updates from a composite child to a host child
-* updates from null to a composite child
-* updates from a composite child to null
-* updates with a host child
-* updates from null to a host child
-* updates from a host child to null
-* updates from a host child to a composite child
-* updates from a composite child to a host child
-* updates from null to a composite child
-* updates from a composite child to null
-* tracks owner correctly
-* purges unmounted components automatically
-* reports update counts
-* does not report top-level wrapper as a root
-* registers inlined text nodes
-* works
-
 src/renderers/__tests__/ReactComponentTreeHook-test.native.js
 * uses displayName or Unknown for classic components
 * uses displayName, name, or ReactComponent for modern components
diff --git a/src/isomorphic/hooks/ReactComponentTreeHook.js b/src/isomorphic/hooks/ReactComponentTreeHook.js
index 9fede1ac22..332c5cac8c 100644
--- a/src/isomorphic/hooks/ReactComponentTreeHook.js
+++ b/src/isomorphic/hooks/ReactComponentTreeHook.js
@@ -182,10 +182,7 @@ function describeID(id: DebugID): string {
     'building stack',
     id
   );
-  if (element && name) {
-    return describeComponentFrame(name || '', element._source, ownerName || '');
-  }
-  return '';
+  return describeComponentFrame(name || '', element && element._source, ownerName || '');
 }
 
 var ReactComponentTreeHook = {
diff --git a/src/renderers/__tests__/ReactComponentTreeHook-test.js b/src/renderers/__tests__/ReactComponentTreeHook-test.js
index a9c19c13eb..0e92d9bfdf 100644
--- a/src/renderers/__tests__/ReactComponentTreeHook-test.js
+++ b/src/renderers/__tests__/ReactComponentTreeHook-test.js
@@ -1736,7 +1736,7 @@ describe('ReactComponentTreeHook', () => {
     expectDev(ReactComponentTreeTestUtils.getRegisteredDisplayNames()).toEqual([]);
   });
 
-  describe('stack addenda', () => {
+  describe.only('stack addenda', () => {
     it('gets created', () => {
       function getAddendum(element) {
         var addendum = ReactComponentTreeHook.getCurrentStackAddendum(element);
diff --git a/src/shared/ReactFiberComponentTreeHook.js b/src/shared/ReactFiberComponentTreeHook.js
index 51cffdb37f..df24a78b0d 100644
--- a/src/shared/ReactFiberComponentTreeHook.js
+++ b/src/shared/ReactFiberComponentTreeHook.js
@@ -22,9 +22,8 @@ var {
 var getComponentName = require('getComponentName');
 
 import type { Fiber } from 'ReactFiber';
-import type { Source } from 'ReactElementType';
 
-function describeComponentFrame(name, source: Source, ownerName) {
+function describeComponentFrame(name, source: any, ownerName) {
   return '\n    in ' + (name || 'Unknown') + (
     source ?
       ' (at ' + source.fileName.replace(/^.*[\\\/]/, '') + ':' +
@@ -48,10 +47,7 @@ function describeFiber(fiber : Fiber) : string {
       if (owner) {
         ownerName = getComponentName(owner);
       }
-      if (source) {
-        return describeComponentFrame(name, source, ownerName);
-      }
-      return '';
+      return describeComponentFrame(name, source, ownerName);
     default:
       return '';
   }