diff --git a/core/fpdfapi/render/fpdf_render_loadimage_embeddertest.cpp b/core/fpdfapi/render/fpdf_render_loadimage_embeddertest.cpp
index 48d7ea3..5103d78 100644
--- a/core/fpdfapi/render/fpdf_render_loadimage_embeddertest.cpp
+++ b/core/fpdfapi/render/fpdf_render_loadimage_embeddertest.cpp
@@ -17,7 +17,7 @@
   FPDF_PAGE page = LoadPage(0);
   ASSERT_TRUE(page);
   ScopedFPDFBitmap bitmap = RenderLoadedPage(page);
-  CompareBitmap(bitmap.get(), 612, 792, "a14d7ee573c1b2456d7bf6b7762823cf");
+  CompareBitmap(bitmap.get(), 612, 792, "1940568c9ba33bac5d0b1ee9558c76b3");
   UnloadPage(page);
 }
 
diff --git a/core/fxcrt/fx_safe_types.h b/core/fxcrt/fx_safe_types.h
index 51eb89c..046a984 100644
--- a/core/fxcrt/fx_safe_types.h
+++ b/core/fxcrt/fx_safe_types.h
@@ -12,6 +12,7 @@
 
 typedef pdfium::base::CheckedNumeric<uint32_t> FX_SAFE_UINT32;
 typedef pdfium::base::CheckedNumeric<int32_t> FX_SAFE_INT32;
+typedef pdfium::base::CheckedNumeric<int64_t> FX_SAFE_INT64;
 typedef pdfium::base::CheckedNumeric<size_t> FX_SAFE_SIZE_T;
 typedef pdfium::base::CheckedNumeric<FX_FILESIZE> FX_SAFE_FILESIZE;
 
diff --git a/core/fxge/dib/cfx_imagestretcher.cpp b/core/fxge/dib/cfx_imagestretcher.cpp
index 9d8e290..1c54e3f 100644
--- a/core/fxge/dib/cfx_imagestretcher.cpp
+++ b/core/fxge/dib/cfx_imagestretcher.cpp
@@ -180,17 +180,28 @@
   int src_height = m_pSource->GetHeight();
   for (; m_LineIndex < result_height; ++m_LineIndex) {
     int dest_y;
-    int src_y;
+    FX_SAFE_INT64 calc_buf;
     if (m_bFlipY) {
       dest_y = result_height - m_LineIndex - 1;
-      src_y = (m_DestHeight - (dest_y + m_ClipRect.top) - 1) * src_height /
-              m_DestHeight;
+      calc_buf = m_DestHeight;
+      calc_buf -= dest_y;
+      calc_buf -= m_ClipRect.top;
+      calc_buf -= 1;
+      calc_buf *= src_height;
+      calc_buf /= m_DestHeight;
     } else {
       dest_y = m_LineIndex;
-      src_y = (dest_y + m_ClipRect.top) * src_height / m_DestHeight;
+      calc_buf = dest_y;
+      calc_buf += m_ClipRect.top;
+      calc_buf *= src_height;
+      calc_buf /= m_DestHeight;
     }
-    src_y = pdfium::clamp(src_y, 0, src_height - 1);
 
+    int src_y;
+    if (!calc_buf.AssignIfValid(&src_y))
+      return false;
+
+    src_y = pdfium::clamp(src_y, 0, src_height - 1);
     if (m_pSource->SkipToScanline(src_y, pPause))
       return true;