diff --git a/core/fpdfapi/edit/cpdf_flateencoder.cpp b/core/fpdfapi/edit/cpdf_flateencoder.cpp
index ba04d7d..7172bf2 100644
--- a/core/fpdfapi/edit/cpdf_flateencoder.cpp
+++ b/core/fpdfapi/edit/cpdf_flateencoder.cpp
@@ -7,6 +7,7 @@
 #include "core/fpdfapi/edit/cpdf_flateencoder.h"
 
 #include <memory>
+#include <utility>
 
 #include "constants/stream_dict_common.h"
 #include "core/fpdfapi/parser/cpdf_dictionary.h"
@@ -40,10 +41,10 @@
   }
 
   // TODO(thestig): Move to Init() and check return value.
-  uint8_t* buffer = nullptr;
+  std::unique_ptr<uint8_t, FxFreeDeleter> buffer;
   ::FlateEncode(m_pAcc->GetSpan(), &buffer, &m_dwSize);
 
-  m_pData = std::unique_ptr<uint8_t, FxFreeDeleter>(buffer);
+  m_pData = std::move(buffer);
   m_pClonedDict = ToDictionary(pStream->GetDict()->Clone());
   m_pClonedDict->SetNewFor<CPDF_Number>("Length", static_cast<int>(m_dwSize));
   m_pClonedDict->SetNewFor<CPDF_Name>("Filter", "FlateDecode");
diff --git a/core/fpdfapi/parser/fpdf_parser_decode.cpp b/core/fpdfapi/parser/fpdf_parser_decode.cpp
index 2b27b89..5e496fd 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode.cpp
+++ b/core/fpdfapi/parser/fpdf_parser_decode.cpp
@@ -581,7 +581,7 @@
 }
 
 bool FlateEncode(pdfium::span<const uint8_t> src_span,
-                 uint8_t** dest_buf,
+                 std::unique_ptr<uint8_t, FxFreeDeleter>* dest_buf,
                  uint32_t* dest_size) {
   CCodec_ModuleMgr* pEncoders = CPDF_ModuleMgr::Get()->GetCodecModule();
   return pEncoders->GetFlateModule()->Encode(src_span.data(), src_span.size(),
diff --git a/core/fpdfapi/parser/fpdf_parser_decode.h b/core/fpdfapi/parser/fpdf_parser_decode.h
index 2b7832f..2652630 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode.h
+++ b/core/fpdfapi/parser/fpdf_parser_decode.h
@@ -43,7 +43,7 @@
     const CPDF_Dictionary* pParams);
 
 bool FlateEncode(pdfium::span<const uint8_t> src_span,
-                 uint8_t** dest_buf,
+                 std::unique_ptr<uint8_t, FxFreeDeleter>* dest_buf,
                  uint32_t* dest_size);
 
 uint32_t FlateDecode(pdfium::span<const uint8_t> src_span,
diff --git a/core/fpdfapi/parser/fpdf_parser_decode_embeddertest.cpp b/core/fpdfapi/parser/fpdf_parser_decode_embeddertest.cpp
index 94776e1..4c99394 100644
--- a/core/fpdfapi/parser/fpdf_parser_decode_embeddertest.cpp
+++ b/core/fpdfapi/parser/fpdf_parser_decode_embeddertest.cpp
@@ -37,16 +37,15 @@
 
   for (size_t i = 0; i < FX_ArraySize(flate_encode_cases); ++i) {
     const pdfium::StrFuncTestData& data = flate_encode_cases[i];
-    unsigned char* buf = nullptr;
+    std::unique_ptr<uint8_t, FxFreeDeleter> buf;
     uint32_t buf_size;
     EXPECT_TRUE(FlateEncode({data.input, data.input_size}, &buf, &buf_size));
     ASSERT_TRUE(buf);
     EXPECT_EQ(data.expected_size, buf_size) << " for case " << i;
     if (data.expected_size != buf_size)
       continue;
-    EXPECT_EQ(0, memcmp(data.expected, buf, data.expected_size))
+    EXPECT_EQ(0, memcmp(data.expected, buf.get(), data.expected_size))
         << " for case " << i;
-    FX_Free(buf);
   }
 }
 
diff --git a/core/fxcodec/codec/ccodec_flatemodule.cpp b/core/fxcodec/codec/ccodec_flatemodule.cpp
index f35b958..f447ec5 100644
--- a/core/fxcodec/codec/ccodec_flatemodule.cpp
+++ b/core/fxcodec/codec/ccodec_flatemodule.cpp
@@ -834,14 +834,15 @@
   return ret ? offset : FX_INVALID_OFFSET;
 }
 
-bool CCodec_FlateModule::Encode(const uint8_t* src_buf,
-                                uint32_t src_size,
-                                uint8_t** dest_buf,
-                                uint32_t* dest_size) {
+bool CCodec_FlateModule::Encode(
+    const uint8_t* src_buf,
+    uint32_t src_size,
+    std::unique_ptr<uint8_t, FxFreeDeleter>* dest_buf,
+    uint32_t* dest_size) {
   *dest_size = src_size + src_size / 1000 + 12;
-  *dest_buf = FX_Alloc(uint8_t, *dest_size);
+  dest_buf->reset(FX_Alloc(uint8_t, *dest_size));
   unsigned long temp_size = *dest_size;
-  if (!FlateCompress(*dest_buf, &temp_size, src_buf, src_size))
+  if (!FlateCompress(dest_buf->get(), &temp_size, src_buf, src_size))
     return false;
 
   *dest_size = (uint32_t)temp_size;
diff --git a/core/fxcodec/codec/ccodec_flatemodule.h b/core/fxcodec/codec/ccodec_flatemodule.h
index 591d13d..d58c184 100644
--- a/core/fxcodec/codec/ccodec_flatemodule.h
+++ b/core/fxcodec/codec/ccodec_flatemodule.h
@@ -41,7 +41,7 @@
 
   bool Encode(const uint8_t* src_buf,
               uint32_t src_size,
-              uint8_t** dest_buf,
+              std::unique_ptr<uint8_t, FxFreeDeleter>* dest_buf,
               uint32_t* dest_size);
 };
 
diff --git a/core/fxge/win32/cfx_psrenderer.cpp b/core/fxge/win32/cfx_psrenderer.cpp
index 12795d0..e66e968 100644
--- a/core/fxge/win32/cfx_psrenderer.cpp
+++ b/core/fxge/win32/cfx_psrenderer.cpp
@@ -59,8 +59,10 @@
   uint8_t* dest_buf = nullptr;
   uint32_t dest_size = src_size;
   if (PSLevel >= 3) {
-    if (pEncoders->GetFlateModule()->Encode(src_buf, src_size, &dest_buf,
+    std::unique_ptr<uint8_t, FxFreeDeleter> dest_buf_unique;
+    if (pEncoders->GetFlateModule()->Encode(src_buf, src_size, &dest_buf_unique,
                                             &dest_size)) {
+      dest_buf = dest_buf_unique.release();
       *filter = "/FlateDecode filter ";
     }
   } else {