diff --unified --recursive --text src/aom/av1/encoder/encodeframe_utils.c src.new/aom/av1/encoder/encodeframe_utils.c
--- src/aom/av1/encoder/encodeframe_utils.c	2021-08-11 10:34:21.390313217 -0600
+++ src.new/aom/av1/encoder/encodeframe_utils.c	2021-08-11 10:37:15.550315777 -0600
@@ -162,9 +162,15 @@
   } else if (tx_mode != TX_MODE_SELECT) {
     mbmi->tx_size = tx_size_from_tx_mode(mbmi->bsize, tx_mode);
   } else {
-    BLOCK_SIZE bsize = mbmi->bsize;
-    TX_SIZE min_tx_size = depth_to_tx_size(MAX_TX_DEPTH, bsize);
-    mbmi->tx_size = (TX_SIZE)TXSIZEMAX(mbmi->tx_size, min_tx_size);
+    const BLOCK_SIZE bsize = mbmi->bsize;
+    const TX_SIZE min_tx_size = depth_to_tx_size(MAX_TX_DEPTH, bsize);
+    if (tx_size_wide[min_tx_size] > tx_size_wide[mbmi->tx_size] ||
+        tx_size_high[min_tx_size] > tx_size_high[mbmi->tx_size])
+      mbmi->tx_size = min_tx_size;
+    const TX_SIZE max_tx_size = get_vartx_max_txsize(xd, bsize, 0);
+    if (tx_size_wide[max_tx_size] < tx_size_wide[mbmi->tx_size] ||
+        tx_size_high[max_tx_size] < tx_size_high[mbmi->tx_size])
+      mbmi->tx_size = max_tx_size;
   }
   if (is_inter_block(mbmi)) {
     memset(mbmi->inter_tx_size, mbmi->tx_size, sizeof(mbmi->inter_tx_size));