diff --git a/xpcom/components/nsCategoryManager.cpp b/xpcom/components/nsCategoryManager.cpp
index 4cf42f8afae1..2f205ebb65e8 100644
--- a/xpcom/components/nsCategoryManager.cpp
+++ b/xpcom/components/nsCategoryManager.cpp
@@ -393,6 +393,12 @@ nsCategoryManager::GetSingleton()
 /* static */ void
 nsCategoryManager::Destroy()
 {
+  // The nsMemoryReporterManager gets destroyed before the nsCategoryManager,
+  // so we don't need to unregister the nsCategoryManager as a memory reporter.
+  // In debug builds we assert that unregistering fails, as a way (imperfect
+  // but better than nothing) of testing the "destroyed before" part.
+  MOZ_ASSERT(NS_FAILED(UnregisterWeakMemoryReporter(gCategoryManager)));
+
   delete gCategoryManager;
   gCategoryManager = nullptr;
 }
@@ -418,7 +424,7 @@ nsCategoryManager::nsCategoryManager()
 void
 nsCategoryManager::InitMemoryReporter()
 {
-  RegisterStrongMemoryReporter(this);
+  RegisterWeakMemoryReporter(this);
 }
 
 nsCategoryManager::~nsCategoryManager()