diff --git a/st.c b/st.c
index d6478f5..034954d 100644
--- a/st.c
+++ b/st.c
@@ -1728,6 +1728,7 @@ csihandle(void)
 		}
 		break;
 	case 'S': /* SU -- Scroll <n> line up */
+		if (csiescseq.priv) break;
 		DEFAULT(csiescseq.arg[0], 1);
 		tscrollup(term.top, csiescseq.arg[0]);
 		break;