diff --git a/third_party/libtiff/tif_dirread.c b/third_party/libtiff/tif_dirread.c
index 70611d037..a09ac44e1 100644
--- a/third_party/libtiff/tif_dirread.c
+++ b/third_party/libtiff/tif_dirread.c
@@ -4181,7 +4181,8 @@ TIFFReadDirectory(TIFF* tif)
                     goto bad;
                 }
 
-                memcpy(new_sampleinfo, tif->tif_dir.td_sampleinfo, old_extrasamples * sizeof(uint16));
+                if (old_extrasamples > 0)
+                    memcpy(new_sampleinfo, tif->tif_dir.td_sampleinfo, old_extrasamples * sizeof(uint16));
                 _TIFFsetShortArray(&tif->tif_dir.td_sampleinfo, new_sampleinfo, tif->tif_dir.td_extrasamples);
                 _TIFFfree(new_sampleinfo);
         }
@@ -5773,7 +5774,8 @@ TIFFFetchStripThing(TIFF* tif, TIFFDirEntry* dir, uint32 nstrips, uint64** lpp)
 			_TIFFfree(data);
 			return(0);
 		}
-                _TIFFmemcpy(resizeddata,data,(uint32)dir->tdir_count*sizeof(uint64));
+		if( dir->tdir_count )
+			_TIFFmemcpy(resizeddata,data, (uint32)dir->tdir_count * sizeof(uint64));
                 _TIFFmemset(resizeddata+(uint32)dir->tdir_count,0,(nstrips-(uint32)dir->tdir_count)*sizeof(uint64));
 		_TIFFfree(data);
 		data=resizeddata;