diff --git a/packages/react-devtools-extensions/src/main/index.js b/packages/react-devtools-extensions/src/main/index.js
index 46c42418c331..d7756ca991be 100644
--- a/packages/react-devtools-extensions/src/main/index.js
+++ b/packages/react-devtools-extensions/src/main/index.js
@@ -317,7 +317,7 @@ function createSourcesEditorPanel() {
   }
 
   const sourcesPanel = chrome.devtools.panels.sources;
-  if (!sourcesPanel) {
+  if (!sourcesPanel || !sourcesPanel.createSidebarPane) {
     // Firefox doesn't currently support extending the source panel.
     return;
   }