diff --git a/Source/Core/DiscIO/WIABlob.cpp b/Source/Core/DiscIO/WIABlob.cpp
index 4d4b104242..999d3136ac 100644
--- a/Source/Core/DiscIO/WIABlob.cpp
+++ b/Source/Core/DiscIO/WIABlob.cpp
@@ -1040,7 +1040,7 @@ std::optional<std::vector<u8>> WIARVZFileReader<RVZ>::Compress(Compressor* compr
 {
   if (compressor)
   {
-    if (!compressor->Start() || !compressor->Compress(data, size) || !compressor->End())
+    if (!compressor->Start(size) || !compressor->Compress(data, size) || !compressor->End())
       return std::nullopt;
 
     data = compressor->GetData();
@@ -1564,7 +1564,7 @@ WIARVZFileReader<RVZ>::ProcessAndCompress(CompressThreadState* state, CompressPa
 
     if (state->compressor)
     {
-      if (!state->compressor->Start())
+      if (!state->compressor->Start(entry.exception_lists.size() + entry.main_data.size()))
         return ConversionResultCode::InternalError;
     }
 
diff --git a/Source/Core/DiscIO/WIACompression.cpp b/Source/Core/DiscIO/WIACompression.cpp
index 20d19c4877..4fdf6cd429 100644
--- a/Source/Core/DiscIO/WIACompression.cpp
+++ b/Source/Core/DiscIO/WIACompression.cpp
@@ -446,7 +446,7 @@ PurgeCompressor::PurgeCompressor()
 
 PurgeCompressor::~PurgeCompressor() = default;
 
-bool PurgeCompressor::Start()
+bool PurgeCompressor::Start(std::optional<u64> size)
 {
   m_buffer.clear();
   m_bytes_written = 0;
@@ -550,7 +550,7 @@ Bzip2Compressor::~Bzip2Compressor()
   BZ2_bzCompressEnd(&m_stream);
 }
 
-bool Bzip2Compressor::Start()
+bool Bzip2Compressor::Start(std::optional<u64> size)
 {
   ASSERT_MSG(DISCIO, m_stream.state == nullptr,
              "Called Bzip2Compressor::Start() twice without calling Bzip2Compressor::End()");
@@ -674,7 +674,7 @@ LZMACompressor::~LZMACompressor()
   lzma_end(&m_stream);
 }
 
-bool LZMACompressor::Start()
+bool LZMACompressor::Start(std::optional<u64> size)
 {
   if (m_initialization_failed)
     return false;
@@ -745,8 +745,11 @@ ZstdCompressor::ZstdCompressor(int compression_level)
 {
   m_stream = ZSTD_createCStream();
 
-  if (ZSTD_isError(ZSTD_CCtx_setParameter(m_stream, ZSTD_c_compressionLevel, compression_level)))
+  if (ZSTD_isError(ZSTD_CCtx_setParameter(m_stream, ZSTD_c_compressionLevel, compression_level)) ||
+      ZSTD_isError(ZSTD_CCtx_setParameter(m_stream, ZSTD_c_contentSizeFlag, 0)))
+  {
     m_stream = nullptr;
+  }
 }
 
 ZstdCompressor::~ZstdCompressor()
@@ -754,7 +757,7 @@ ZstdCompressor::~ZstdCompressor()
   ZSTD_freeCStream(m_stream);
 }
 
-bool ZstdCompressor::Start()
+bool ZstdCompressor::Start(std::optional<u64> size)
 {
   if (!m_stream)
     return false;
@@ -762,7 +765,16 @@ bool ZstdCompressor::Start()
   m_buffer.clear();
   m_out_buffer = {};
 
-  return !ZSTD_isError(ZSTD_CCtx_reset(m_stream, ZSTD_reset_session_only));
+  if (ZSTD_isError(ZSTD_CCtx_reset(m_stream, ZSTD_reset_session_only)))
+    return false;
+
+  if (size)
+  {
+    if (ZSTD_isError(ZSTD_CCtx_setPledgedSrcSize(m_stream, *size)))
+      return false;
+  }
+
+  return true;
 }
 
 bool ZstdCompressor::Compress(const u8* data, size_t size)
diff --git a/Source/Core/DiscIO/WIACompression.h b/Source/Core/DiscIO/WIACompression.h
index 37e8cf3dc3..2a6bbc9f8d 100644
--- a/Source/Core/DiscIO/WIACompression.h
+++ b/Source/Core/DiscIO/WIACompression.h
@@ -154,7 +154,7 @@ public:
   // First call Start, then AddDataOnlyForPurgeHashing/Compress any number of times,
   // then End, then GetData/GetSize any number of times.
 
-  virtual bool Start() = 0;
+  virtual bool Start(std::optional<u64> size) = 0;
   virtual bool AddPrecedingDataOnlyForPurgeHashing(const u8* data, size_t size) { return true; }
   virtual bool Compress(const u8* data, size_t size) = 0;
   virtual bool End() = 0;
@@ -169,7 +169,7 @@ public:
   PurgeCompressor();
   ~PurgeCompressor();
 
-  bool Start() override;
+  bool Start(std::optional<u64> size) override;
   bool AddPrecedingDataOnlyForPurgeHashing(const u8* data, size_t size) override;
   bool Compress(const u8* data, size_t size) override;
   bool End() override;
@@ -189,7 +189,7 @@ public:
   Bzip2Compressor(int compression_level);
   ~Bzip2Compressor();
 
-  bool Start() override;
+  bool Start(std::optional<u64> size) override;
   bool Compress(const u8* data, size_t size) override;
   bool End() override;
 
@@ -211,7 +211,7 @@ public:
                  u8* compressor_data_size_out);
   ~LZMACompressor();
 
-  bool Start() override;
+  bool Start(std::optional<u64> size) override;
   bool Compress(const u8* data, size_t size) override;
   bool End() override;
 
@@ -234,7 +234,7 @@ public:
   ZstdCompressor(int compression_level);
   ~ZstdCompressor();
 
-  bool Start() override;
+  bool Start(std::optional<u64> size) override;
   bool Compress(const u8* data, size_t size) override;
   bool End() override;