diff --git a/netwerk/base/src/nsSocketTransportService2.cpp b/netwerk/base/src/nsSocketTransportService2.cpp
index c36bebd069c8..a27d2fa50afb 100644
--- a/netwerk/base/src/nsSocketTransportService2.cpp
+++ b/netwerk/base/src/nsSocketTransportService2.cpp
@@ -365,6 +365,9 @@ nsSocketTransportService::Init()
     if (mInitialized)
         return NS_OK;
 
+    if (mShuttingDown)
+        return NS_ERROR_UNEXPECTED;
+
     if (!mThreadEvent) {
         mThreadEvent = PR_NewPollableEvent();
         //
@@ -401,6 +404,9 @@ nsSocketTransportService::Shutdown()
     if (!mInitialized)
         return NS_OK;
 
+    if (mShuttingDown)
+        return NS_ERROR_UNEXPECTED;
+
     {
         nsAutoLock lock(mLock);