diff --git a/core/fpdfapi/parser/cpdf_stream.cpp b/core/fpdfapi/parser/cpdf_stream.cpp
index e186bc1..d62b456 100644
--- a/core/fpdfapi/parser/cpdf_stream.cpp
+++ b/core/fpdfapi/parser/cpdf_stream.cpp
@@ -113,7 +113,7 @@
 bool CPDF_Stream::ReadRawData(FX_FILESIZE offset,
                               uint8_t* buf,
                               uint32_t size) const {
-  if (m_bMemoryBased && m_pFile)
+  if (!m_bMemoryBased && m_pFile)
     return m_pFile->ReadBlock(buf, offset, size);
 
   if (m_pDataBuf)