diff --git a/netwerk/base/nsMIMEInputStream.cpp b/netwerk/base/nsMIMEInputStream.cpp
index c7dca0fb6de2..2fba15901dea 100644
--- a/netwerk/base/nsMIMEInputStream.cpp
+++ b/netwerk/base/nsMIMEInputStream.cpp
@@ -45,8 +45,8 @@ private:
 
     void InitStreams();
 
-    struct ReadSegmentsState {
-        nsIInputStream* mThisStream;
+    struct MOZ_STACK_CLASS ReadSegmentsState {
+        nsCOMPtr<nsIInputStream> mThisStream;
         nsWriteSegmentFun mWriter;
         void* mClosure;
     };
diff --git a/xpcom/io/nsMultiplexInputStream.cpp b/xpcom/io/nsMultiplexInputStream.cpp
index 7bfc6b1a4a9a..8cc758df30f3 100644
--- a/xpcom/io/nsMultiplexInputStream.cpp
+++ b/xpcom/io/nsMultiplexInputStream.cpp
@@ -46,9 +46,9 @@ private:
   {
   }
 
-  struct ReadSegmentsState
+  struct MOZ_STACK_CLASS ReadSegmentsState
   {
-    nsIInputStream* mThisStream;
+    nsCOMPtr<nsIInputStream> mThisStream;
     uint32_t mOffset;
     nsWriteSegmentFun mWriter;
     void* mClosure;