diff --git a/input.c b/input.c
index d22ee1a8..590a157d 100644
--- a/input.c
+++ b/input.c
@@ -2101,6 +2101,7 @@ input_csi_dispatch_sgr(struct input_ctx *ictx)
 			gc->attr |= GRID_ATTR_UNDERSCORE;
 			break;
 		case 5:
+		case 6:
 			gc->attr |= GRID_ATTR_BLINK;
 			break;
 		case 7:
@@ -2112,6 +2113,10 @@ input_csi_dispatch_sgr(struct input_ctx *ictx)
 		case 9:
 			gc->attr |= GRID_ATTR_STRIKETHROUGH;
 			break;
+		case 21:
+			gc->attr &= ~GRID_ATTR_ALL_UNDERSCORE;
+			gc->attr |= GRID_ATTR_UNDERSCORE_2;
+			break;
 		case 22:
 			gc->attr &= ~(GRID_ATTR_BRIGHT|GRID_ATTR_DIM);
 			break;