diff --git a/scripts/fiber/tests-failing.txt b/scripts/fiber/tests-failing.txt
index 8d705c30e8..04626aca6a 100644
--- a/scripts/fiber/tests-failing.txt
+++ b/scripts/fiber/tests-failing.txt
@@ -18,6 +18,10 @@ src/isomorphic/modern/element/__tests__/ReactJSXElementValidator-test.js
 src/renderers/dom/__tests__/ReactDOMProduction-test.js
 * should throw with an error code in production
 
+src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
+* should keep track of namespace across portals (medium)
+* should unwind namespaces on caught errors in a portal
+
 src/renderers/dom/shared/__tests__/ReactDOM-test.js
 * throws in render() if the mount callback is not a function
 * throws in render() if the update callback is not a function
diff --git a/scripts/fiber/tests-passing.txt b/scripts/fiber/tests-passing.txt
index 7143e78caa..119983286a 100644
--- a/scripts/fiber/tests-passing.txt
+++ b/scripts/fiber/tests-passing.txt
@@ -515,11 +515,9 @@ src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
 * should render many portals
 * should render nested portals
 * should keep track of namespace across portals (simple)
-* should keep track of namespace across portals (medium)
 * should keep track of namespace across portals (complex)
 * should unwind namespaces on uncaught errors
 * should unwind namespaces on caught errors
-* should unwind namespaces on caught errors in a portal
 * should pass portal context when rendering subtree elsewhere
 * should update portal context if it changes due to setState
 * should update portal context if it changes due to re-render
diff --git a/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js b/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
index 29f01844bc..fd20ef8a8c 100644
--- a/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
+++ b/src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
@@ -400,6 +400,19 @@ describe('ReactDOMFiber', () => {
     });
 
     it('should keep track of namespace across portals (medium)', () => {
+      assertNamespacesMatch(
+        <svg {...expectSVG}>
+          <image {...expectSVG} />
+          {usePortal(
+            <div {...expectHTML} />
+          )}
+          <image {...expectSVG} />
+          {usePortal(
+            <div {...expectHTML} />
+          )}
+          <image {...expectSVG} />
+        </svg>
+      );
       assertNamespacesMatch(
         <div {...expectHTML}>
           <math {...expectMath}>
@@ -613,15 +626,9 @@ describe('ReactDOMFiber', () => {
               </div>
             )}
           </ErrorBoundary>
-          {
-            /*
-            * TODO: enable. Currently this leads to stack overflow
-            * but it might be a bug in error boundaries rather than SVG or portals.
-            usePortal(
-              <div {...expectHTML} />
-            )
-            */
-          }
+          {usePortal(
+            <div {...expectHTML} />
+          )}
         </svg>
       );
     });