diff --git a/web/handlers.go b/web/handlers.go
index 0f5a4d17d4..15675878f9 100644
--- a/web/handlers.go
+++ b/web/handlers.go
@@ -177,7 +177,13 @@ func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		// Add unsafe-eval to the content security policy for faster source maps in development mode
 		devCSP := ""
 		if model.BuildNumber == "dev" {
-			devCSP = " 'unsafe-eval'"
+			devCSP += " 'unsafe-eval'"
+		}
+
+		// Add unsafe-inline to unlock extensions like React & Redux DevTools in Firefox
+		// see https://github.com/reduxjs/redux-devtools/issues/380
+		if model.BuildNumber == "dev" {
+			devCSP += " 'unsafe-inline'"
 		}
 
 		// Set content security policy. This is also specified in the root.html of the webapp in a meta tag.