diff --git a/core/src/fxcodec/codec/codec_int.h b/core/src/fxcodec/codec/codec_int.h
index bc2aac8..2910589 100644
--- a/core/src/fxcodec/codec/codec_int.h
+++ b/core/src/fxcodec/codec/codec_int.h
@@ -57,7 +57,7 @@
  protected:
   class ImageDataCache {
    public:
-    ImageDataCache(int width, int height, int pitch);
+    ImageDataCache(int width, int height, FX_DWORD pitch);
     ~ImageDataCache();
 
     bool AllocateCache();
@@ -74,7 +74,7 @@
 
     const int m_Width;
     const int m_Height;
-    const int m_Pitch;
+    const FX_DWORD m_Pitch;
     int m_nCachedLines;
     nonstd::unique_ptr<uint8_t, FxFreeDeleter> m_Data;
   };
@@ -92,7 +92,7 @@
   int m_OutputHeight;
   int m_nComps;
   int m_bpc;
-  int m_Pitch;
+  FX_DWORD m_Pitch;
   FX_BOOL m_bColorTransformed;
   int m_NextLine;
   uint8_t* m_pLastScanline;
diff --git a/core/src/fxcodec/codec/fx_codec.cpp b/core/src/fxcodec/codec/fx_codec.cpp
index 46f479e..9e284e4 100644
--- a/core/src/fxcodec/codec/fx_codec.cpp
+++ b/core/src/fxcodec/codec/fx_codec.cpp
@@ -23,7 +23,7 @@
 
 CCodec_ScanlineDecoder::ImageDataCache::ImageDataCache(int width,
                                                        int height,
-                                                       int pitch)
+                                                       FX_DWORD pitch)
     : m_Width(width), m_Height(height), m_Pitch(pitch), m_nCachedLines(0) {
 }
 
@@ -31,7 +31,7 @@
 }
 
 bool CCodec_ScanlineDecoder::ImageDataCache::AllocateCache() {
-  if (m_Pitch <= 0 || m_Height < 0)
+  if (m_Pitch == 0 || m_Height < 0)
     return false;
 
   FX_SAFE_SIZE_T size = m_Pitch;
@@ -45,7 +45,7 @@
 
 void CCodec_ScanlineDecoder::ImageDataCache::AppendLine(const uint8_t* line) {
   // If the callers adds more lines than there is room, fail.
-  if (m_Pitch <= 0 || m_nCachedLines >= m_Height) {
+  if (m_Pitch == 0 || m_nCachedLines >= m_Height) {
     NOTREACHED();
     return;
   }
@@ -56,7 +56,7 @@
 }
 
 const uint8_t* CCodec_ScanlineDecoder::ImageDataCache::GetLine(int line) const {
-  if (m_Pitch <= 0 || line < 0 || line >= m_nCachedLines)
+  if (m_Pitch == 0 || line < 0 || line >= m_nCachedLines)
     return nullptr;
 
   size_t offset = m_Pitch;
@@ -338,8 +338,19 @@
   m_bpc = bpc;
   m_bColorTransformed = FALSE;
   m_DownScale = 1;
-  m_Pitch = (width * nComps * bpc + 31) / 32 * 4;
-  m_dwLineBytes = (width * nComps * bpc + 7) / 8;
+  // Aligning the pitch to 4 bytes requires an integer overflow check.
+  FX_SAFE_DWORD pitch = width;
+  pitch *= nComps;
+  pitch *= bpc;
+  pitch += 31;
+  pitch /= 32;
+  pitch *= 4;
+  if (!pitch.IsValid()) {
+    return FALSE;
+  }
+  m_Pitch = pitch.ValueOrDie();
+  // Overflow should already have been checked before this is called.
+  m_dwLineBytes = (static_cast<FX_DWORD>(width) * nComps * bpc + 7) / 8;
   m_pScanline = FX_Alloc(uint8_t, m_Pitch);
   return CheckDestSize();
 }
diff --git a/core/src/fxcodec/codec/fx_codec_fax.cpp b/core/src/fxcodec/codec/fx_codec_fax.cpp
index 5af1d9e..daa8a07 100644
--- a/core/src/fxcodec/codec/fx_codec_fax.cpp
+++ b/core/src/fxcodec/codec/fx_codec_fax.cpp
@@ -656,7 +656,8 @@
   if (m_OrigHeight == 0) {
     m_OrigHeight = height;
   }
-  m_Pitch = (m_OrigWidth + 31) / 32 * 4;
+  // Should not overflow. Checked by FPDFAPI_CreateFaxDecoder.
+  m_Pitch = (static_cast<FX_DWORD>(m_OrigWidth) + 31) / 32 * 4;
   m_OutputWidth = m_OrigWidth;
   m_OutputHeight = m_OrigHeight;
   m_pScanlineBuf = FX_Alloc(uint8_t, m_Pitch);
@@ -716,7 +717,7 @@
     }
   }
   if (m_bBlack) {
-    for (int i = 0; i < m_Pitch; i++) {
+    for (FX_DWORD i = 0; i < m_Pitch; i++) {
       m_pScanlineBuf[i] = ~m_pScanlineBuf[i];
     }
   }
diff --git a/core/src/fxcodec/codec/fx_codec_flate.cpp b/core/src/fxcodec/codec/fx_codec_flate.cpp
index 519ff00..34356e1 100644
--- a/core/src/fxcodec/codec/fx_codec_flate.cpp
+++ b/core/src/fxcodec/codec/fx_codec_flate.cpp
@@ -558,7 +558,7 @@
 }
 
 void TIFF_PredictLine(uint8_t* dest_buf,
-                      int row_size,
+                      FX_DWORD row_size,
                       int BitsPerComponent,
                       int Colors,
                       int Columns) {
@@ -582,7 +582,7 @@
   }
   int BytesPerPixel = BitsPerComponent * Colors / 8;
   if (BitsPerComponent == 16) {
-    for (int i = BytesPerPixel; i < row_size; i += 2) {
+    for (FX_DWORD i = BytesPerPixel; i < row_size; i += 2) {
       FX_WORD pixel =
           (dest_buf[i - BytesPerPixel] << 8) | dest_buf[i - BytesPerPixel + 1];
       pixel += (dest_buf[i] << 8) | dest_buf[i + 1];
@@ -590,7 +590,7 @@
       dest_buf[i + 1] = (uint8_t)pixel;
     }
   } else {
-    for (int i = BytesPerPixel; i < row_size; i++) {
+    for (FX_DWORD i = BytesPerPixel; i < row_size; i++) {
       dest_buf[i] += dest_buf[i - BytesPerPixel];
     }
   }
@@ -761,7 +761,11 @@
   uint8_t* m_pPredictBuffer;
   uint8_t* m_pPredictRaw;
   int m_Predictor;
-  int m_Colors, m_BitsPerComponent, m_Columns, m_PredictPitch, m_LeftOver;
+  int m_Colors;
+  int m_BitsPerComponent;
+  int m_Columns;
+  FX_DWORD m_PredictPitch;
+  size_t m_LeftOver;
 };
 
 CCodec_FlateScanlineDecoder::CCodec_FlateScanlineDecoder() {
@@ -798,7 +802,7 @@
   m_nComps = nComps;
   m_bpc = bpc;
   m_bColorTransformed = FALSE;
-  m_Pitch = (width * nComps * bpc + 7) / 8;
+  m_Pitch = (static_cast<FX_DWORD>(width) * nComps * bpc + 7) / 8;
   m_pScanline = FX_Alloc(uint8_t, m_Pitch);
   m_Predictor = 0;
   if (predictor) {
@@ -816,7 +820,10 @@
       m_Colors = Colors;
       m_BitsPerComponent = BitsPerComponent;
       m_Columns = Columns;
-      m_PredictPitch = (m_BitsPerComponent * m_Colors * m_Columns + 7) / 8;
+      m_PredictPitch =
+          (static_cast<FX_DWORD>(m_BitsPerComponent) * m_Colors * m_Columns +
+           7) /
+          8;
       m_pLastLine = FX_Alloc(uint8_t, m_PredictPitch);
       m_pPredictRaw = FX_Alloc(uint8_t, m_PredictPitch + 1);
       m_pPredictBuffer = FX_Alloc(uint8_t, m_PredictPitch);
@@ -849,8 +856,9 @@
                          m_OutputWidth);
       }
     } else {
-      int bytes_to_go = m_Pitch;
-      int read_leftover = m_LeftOver > bytes_to_go ? bytes_to_go : m_LeftOver;
+      size_t bytes_to_go = m_Pitch;
+      size_t read_leftover =
+          m_LeftOver > bytes_to_go ? bytes_to_go : m_LeftOver;
       if (read_leftover) {
         FXSYS_memcpy(m_pScanline,
                      m_pPredictBuffer + m_PredictPitch - m_LeftOver,
@@ -869,7 +877,7 @@
           TIFF_PredictLine(m_pPredictBuffer, m_PredictPitch, m_BitsPerComponent,
                            m_Colors, m_Columns);
         }
-        int read_bytes =
+        size_t read_bytes =
             m_PredictPitch > bytes_to_go ? bytes_to_go : m_PredictPitch;
         FXSYS_memcpy(m_pScanline + m_Pitch - bytes_to_go, m_pPredictBuffer,
                      read_bytes);
diff --git a/core/src/fxcodec/codec/fx_codec_jpeg.cpp b/core/src/fxcodec/codec/fx_codec_jpeg.cpp
index efd83f8..0a38fc8 100644
--- a/core/src/fxcodec/codec/fx_codec_jpeg.cpp
+++ b/core/src/fxcodec/codec/fx_codec_jpeg.cpp
@@ -426,7 +426,9 @@
   if ((int)cinfo.image_width < width) {
     return FALSE;
   }
-  m_Pitch = (cinfo.image_width * cinfo.num_components + 3) / 4 * 4;
+  m_Pitch =
+      (static_cast<FX_DWORD>(cinfo.image_width) * cinfo.num_components + 3) /
+      4 * 4;
   m_pScanlineBuf = FX_Alloc(uint8_t, m_Pitch);
   m_nComps = cinfo.num_components;
   m_bpc = 8;
@@ -464,7 +466,7 @@
       FX_GetDownsampleRatio(m_OrigWidth, m_OrigHeight, dest_width, dest_height);
   m_OutputWidth = (m_OrigWidth + m_DownScale - 1) / m_DownScale;
   m_OutputHeight = (m_OrigHeight + m_DownScale - 1) / m_DownScale;
-  m_Pitch = (m_OutputWidth * m_nComps + 3) / 4 * 4;
+  m_Pitch = (static_cast<FX_DWORD>(m_OutputWidth) * m_nComps + 3) / 4 * 4;
   if (old_scale != m_DownScale) {
     m_NextLine = -1;
   }