diff --git a/pcsx2/CDVD/CsoFileReader.cpp b/pcsx2/CDVD/CsoFileReader.cpp
index 44f8ca5b1e..0f118202b0 100644
--- a/pcsx2/CDVD/CsoFileReader.cpp
+++ b/pcsx2/CDVD/CsoFileReader.cpp
@@ -140,6 +140,15 @@ bool CsoFileReader::InitializeBuffers() {
 		return false;
 	}
 
+	m_z_stream = new z_stream;
+	m_z_stream->zalloc = Z_NULL;
+	m_z_stream->zfree = Z_NULL;
+	m_z_stream->opaque = Z_NULL;
+	if (inflateInit2(m_z_stream, -15) != Z_OK) {
+		Console.Error("Unable to initialize zlib for CSO decompression.");
+		return false;
+	}
+
 	return true;
 }
 
@@ -148,20 +157,24 @@ void CsoFileReader::Close() {
 
 	if (m_src) {
 		fclose(m_src);
-		m_src = 0;
+		m_src = NULL;
+	}
+	if (m_z_stream) {
+		inflateEnd(m_z_stream);
+		m_z_stream = NULL;
 	}
 
 	if (m_readBuffer) {
 		delete[] m_readBuffer;
-		m_readBuffer = 0;
+		m_readBuffer = NULL;
 	}
 	if (m_zlibBuffer) {
 		delete[] m_zlibBuffer;
-		m_zlibBuffer = 0;
+		m_zlibBuffer = NULL;
 	}
 	if (m_index) {
 		delete[] m_index;
-		m_index = 0;
+		m_index = NULL;
 	}
 }
 
@@ -238,41 +251,33 @@ int CsoFileReader::ReadFromFrame(u8 *dest, u64 pos, u64 maxBytes) {
 }
 
 bool CsoFileReader::DecompressFrame(u32 frame, u32 readBufferSize) {
-	z_stream z;
-	z.zalloc = Z_NULL;
-	z.zfree = Z_NULL;
-	z.opaque = Z_NULL;
-	if (inflateInit2(&z, -15) != Z_OK) {
-		Console.Error("Unable to initialize zlib for CSO decompression.");
-		return false;
-	}
+	m_z_stream->next_in = m_readBuffer;
+	m_z_stream->avail_in = readBufferSize;
+	m_z_stream->next_out = m_zlibBuffer;
+	m_z_stream->avail_out = m_frameSize;
 
-	z.next_in = m_readBuffer;
-	z.avail_in = readBufferSize;
-	z.next_out = m_zlibBuffer;
-	z.avail_out = m_frameSize;
-
-	int status = inflate(&z, Z_FINISH);
-	if (status != Z_STREAM_END || z.total_out != m_frameSize) {
-		inflateEnd(&z);
+	int status = inflate(m_z_stream, Z_FINISH);
+	bool success = status == Z_STREAM_END && m_z_stream->total_out == m_frameSize;
+	if (success) {
+		// Our buffer now contains this frame.
+		m_zlibBufferFrame = frame;
+	} else {
 		Console.Error("Unable to decompress CSO frame using zlib.");
-		return false;
+		m_zlibBufferFrame = (u32)-1;
 	}
-	inflateEnd(&z);
 
-	// Our buffer now contains this frame.
-	m_zlibBufferFrame = frame;
-	return true;
+	inflateReset(m_z_stream);
+	return success;
 }
 
 void CsoFileReader::BeginRead(void* pBuffer, uint sector, uint count) {
 	// TODO: No async support yet, implement as sync.
-	mBytesRead = ReadSync(pBuffer, sector, count);
+	m_bytesRead = ReadSync(pBuffer, sector, count);
 }
 
 int CsoFileReader::FinishRead() {
-	int res = mBytesRead;
-	mBytesRead = -1;
+	int res = m_bytesRead;
+	m_bytesRead = -1;
 	return res;
 }
 
diff --git a/pcsx2/CDVD/CsoFileReader.h b/pcsx2/CDVD/CsoFileReader.h
index 2363053741..1eac7ae270 100644
--- a/pcsx2/CDVD/CsoFileReader.h
+++ b/pcsx2/CDVD/CsoFileReader.h
@@ -18,6 +18,7 @@
 #include "AsyncFileReader.h"
 
 struct CsoHeader;
+typedef struct z_stream_s z_stream;
 
 class CsoFileReader : public AsyncFileReader
 {
@@ -28,7 +29,9 @@ public:
 		m_zlibBuffer(0),
 		m_index(0),
 		m_totalSize(0),
-		m_src(0) {
+		m_src(0),
+		m_z_stream(0),
+		m_bytesRead(0) {
 		m_blocksize = 2048;
 	};
 
@@ -69,6 +72,7 @@ private:
 	u64 m_totalSize;
 	// The actual source cso file handle.
 	FILE* m_src;
+	z_stream* m_z_stream;
 	// The result of a read is stored here between BeginRead() and FinishRead().
-	int mBytesRead;
+	int m_bytesRead;
 };