--- core/fxcodec/lbmp/fx_bmp.h
+++ core/fxcodec/lbmp/fx_bmp.h
@@ -126,7 +126,7 @@ class BMPDecompressor {
 class CBmpContext : public CCodec_BmpModule::Context {
  public:
   CBmpContext(CCodec_BmpModule* pModule, CCodec_BmpModule::Delegate* pDelegate);
-  ~CBmpContext() override;
+  ~CBmpContext() override {}
 
   BMPDecompressor m_Bmp;
   UnownedPtr<CCodec_BmpModule> const m_pModule;
--- core/fxge/cfx_facecache.cpp
+++ core/fxge/cfx_facecache.cpp
@@ -223,7 +223,8 @@ std::unique_ptr<CFX_GlyphBitmap> CFX_FaceCache::RenderGlyph(
       }
     }
   } else {
-    memset(pDestBuf, 0, dest_pitch * bmheight);
+    if (dest_pitch != 0 && bmheight != 0)
+      memset(pDestBuf, 0, dest_pitch * bmheight);
     if (anti_alias == FXFT_RENDER_MODE_MONO &&
         FXFT_Get_Bitmap_PixelMode(FXFT_Get_Glyph_Bitmap(m_Face)) ==
             FXFT_PIXEL_MODE_MONO) {
--- third_party/agg23/agg_rasterizer_scanline_aa.h
+++ third_party/agg23/agg_rasterizer_scanline_aa.h
@@ -349,14 +349,14 @@ public:
                     cover += cur_cell->cover;
                 }
                 if(area) {
-                    alpha = calculate_alpha((cover << (poly_base_shift + 1)) - area, no_smooth);
+                    alpha = calculate_alpha(int(unsigned(cover) << (poly_base_shift + 1)) - area, no_smooth);
                     if(alpha) {
                         sl.add_cell(x, alpha);
                     }
                     x++;
                 }
                 if(num_cells && cur_cell->x > x) {
-                    alpha = calculate_alpha(cover << (poly_base_shift + 1), no_smooth);
+                    alpha = calculate_alpha(unsigned(cover) << (poly_base_shift + 1), no_smooth);
                     if(alpha) {
                         sl.add_span(x, cur_cell->x - x, alpha);
                     }