diff --git a/libtiff/tif_dirread.c b/libtiff/tif_dirread.c
index 3c5adb2b..4950b82c 100644
--- a/libtiff/tif_dirread.c
+++ b/libtiff/tif_dirread.c
@@ -864,7 +864,7 @@ static enum TIFFReadDirEntryErr TIFFReadDirEntryArrayWithLimit(
 	datasize=(*count)*typesize;
 	assert((tmsize_t)datasize>0);
 
-	if( isMapped(tif) && datasize > (uint32)tif->tif_size )
+	if( isMapped(tif) && datasize > (uint64)tif->tif_size )
 		return TIFFReadDirEntryErrIo;
 
 	if( !isMapped(tif) &&
@@ -3400,7 +3400,7 @@ TIFFReadDirEntryData(TIFF* tif, uint64 offset, tmsize_t size, void* dest)
                     return TIFFReadDirEntryErrIo;
                 }
 		mb=ma+size;
-		if (mb > (size_t)tif->tif_size)
+		if (mb > (uint64)tif->tif_size)
 			return(TIFFReadDirEntryErrIo);
 		_TIFFmemcpy(dest,tif->tif_base+ma,size);
 	}