diff --git a/renderdoc/serialise/streamio.cpp b/renderdoc/serialise/streamio.cpp
index cb6c8b95a..21e35d18b 100644
--- a/renderdoc/serialise/streamio.cpp
+++ b/renderdoc/serialise/streamio.cpp
@@ -270,7 +270,7 @@ bool StreamReader::Reserve(uint64_t numBytes)
 
 bool StreamReader::ReadLargeBuffer(void *buffer, uint64_t length)
 {
-  RDCASSERT(m_Sock || m_File || m_Decompressor);
+  RDCASSERT(m_File || m_Decompressor);
 
   byte *dest = (byte *)buffer;
 
@@ -398,6 +398,9 @@ bool StreamReader::ReadFromExternal(void *buffer, uint64_t length)
       // first get the required data blocking (this will sleep the thread until it comes in).
       byte *readDest = (byte *)buffer;
 
+      // we expect to be reading into our window buffer
+      RDCASSERT(readDest >= m_BufferBase && readDest <= m_BufferBase + m_BufferSize);
+
       success = m_Sock->RecvDataBlocking(readDest, (uint32_t)length);
 
       if(success)
@@ -407,6 +410,12 @@ bool StreamReader::ReadFromExternal(void *buffer, uint64_t length)
 
         uint32_t bufSize = uint32_t(m_BufferSize - m_InputSize);
 
+        if(m_InputSize > m_BufferSize)
+        {
+          bufSize = 0;
+          RDCERR("Invalid read in ReadFromExternal!");
+        }
+
         // now read more, as much as possible, to try and batch future reads
         success = m_Sock->RecvDataNonBlocking(readDest, bufSize);
 
diff --git a/renderdoc/serialise/streamio.h b/renderdoc/serialise/streamio.h
index ae1b0bc8a..fa232ae10 100644
--- a/renderdoc/serialise/streamio.h
+++ b/renderdoc/serialise/streamio.h
@@ -180,7 +180,9 @@ public:
         // and larger by just skating over the limit each time, but that's fine because the main
         // case we want to catch is a window that's only a few MB and then suddenly we read 100s of
         // MB.
-        if(numBytes >= 10 * 1024 * 1024 && Available() + 128 < numBytes)
+        // We don't do this on sockets since we want to opportunistically read more into the window
+        // to batch lots of small reads together.
+        if(m_Sock == NULL && numBytes >= 10 * 1024 * 1024 && Available() + 128 < numBytes)
         {
           success = ReadLargeBuffer(data, numBytes);
           alreadyread = true;