diff --git a/csi.c b/csi.c
index 21a94625..873d45a7 100644
--- a/csi.c
+++ b/csi.c
@@ -321,6 +321,204 @@ csi_sgr(struct terminal *term)
     }
 }
 
+static void
+decset_decrst(struct terminal *term, unsigned param, bool enable)
+{
+#if defined(_DEBUG)
+    /* For UNHANDLED() */
+    int UNUSED final = enable ? 'h' : 'l';
+#endif
+
+    switch (param) {
+    case 1:
+        term->cursor_keys_mode =
+            enable ? CURSOR_KEYS_APPLICATION : CURSOR_KEYS_NORMAL;
+        break;
+
+    case 3:
+        if (enable)
+            LOG_WARN("unimplemented: 132 column mode (DECCOLM)");
+
+        term_erase(
+            term,
+            &(struct coord){0, 0},
+            &(struct coord){term->cols - 1, term->rows - 1});
+        term_cursor_home(term);
+        break;
+
+    case 4:
+        /* DECSCLM - Smooth scroll */
+        if (enable)
+            LOG_WARN("unimplemented: Smooth (Slow) Scroll (DECSCLM)");
+        break;
+
+    case 5:
+        term->reverse = enable;
+        term_damage_all(term);
+        break;
+
+    case 6: { /* DECOM */
+        term->origin = enable ? ORIGIN_RELATIVE : ORIGIN_ABSOLUTE;
+        term_cursor_home(term);
+        break;
+    }
+
+    case 7:
+        /* DECAWM */
+        term->auto_margin = enable;
+        term->grid->cursor.lcf = false;
+        break;
+
+    case 9:
+        if (enable)
+            LOG_WARN("unimplemented: X10 mouse tracking mode");
+        else
+            term->mouse_tracking = MOUSE_NONE;
+        break;
+
+    case 12:
+        if (enable)
+            term_cursor_blink_enable(term);
+        else
+            term_cursor_blink_disable(term);
+        break;
+
+    case 25:
+        term->hide_cursor = !enable;
+        break;
+
+    case 1000:
+        term->mouse_tracking = enable ? MOUSE_CLICK : MOUSE_NONE;
+        term_xcursor_update(term);
+        break;
+
+    case 1001:
+        if (enable)
+            LOG_WARN("unimplemented: highlight mouse tracking");
+        break;
+
+    case 1002:
+        term->mouse_tracking = enable ? MOUSE_DRAG : MOUSE_NONE;
+        term_xcursor_update(term);
+        break;
+
+    case 1003:
+        term->mouse_tracking = enable ? MOUSE_MOTION : MOUSE_NONE;
+        term_xcursor_update(term);
+        break;
+
+    case 1004:
+        term->focus_events = enable;
+        break;
+
+    case 1005:
+        if (enable)
+            LOG_WARN("unimplemented: mouse reporting mode: UTF-8");
+        else
+            term->mouse_reporting = MOUSE_NONE;
+        break;
+
+    case 1006:
+        if (enable)
+            LOG_DBG("mouse reporting mode: SGR");
+        term->mouse_reporting = enable ? MOUSE_SGR : MOUSE_NORMAL;
+        break;
+
+    case 1007:
+        term->alt_scrolling = enable;
+        break;
+
+    case 1015:
+        if (enable)
+            LOG_DBG("mouse reporting mode: urxvt");
+        term->mouse_reporting = enable ? MOUSE_URXVT : MOUSE_NORMAL;
+        break;
+
+    case 1034:
+        /* smm */
+        LOG_DBG("%s 8-bit meta mode", enable ? "enabling" : "disabling");
+        term->meta.eight_bit = enable;
+        break;
+
+    case 1036:
+        /* metaSendsEscape */
+        LOG_DBG("%s meta-sends-escape", enable ? "enabling" : "disabling");
+        term->meta.esc_prefix = enable;
+        break;
+
+#if 0
+    case 1042:
+        LOG_WARN("unimplemented: 'urgency' window manager hint on ctrl-g");
+        break;
+
+    case 1043:
+        LOG_WARN("unimplemented: raise window on ctrl-g");
+        break;
+#endif
+
+    case 1049:
+        if (enable && term->grid != &term->alt) {
+            selection_cancel(term);
+
+            term->grid = &term->alt;
+
+            term_cursor_to(
+                term,
+                min(term->grid->cursor.point.row, term->rows - 1),
+                min(term->grid->cursor.point.col, term->cols - 1));
+
+            tll_free(term->alt.scroll_damage);
+
+            term_erase(
+                term,
+                &(struct coord){0, 0},
+                &(struct coord){term->cols - 1, term->rows - 1});
+        }
+
+        else if (!enable && term->grid == &term->alt) {
+            selection_cancel(term);
+
+            term->grid = &term->normal;
+
+            term_cursor_to(
+                term,
+                min(term->grid->cursor.point.row, term->rows - 1),
+                min(term->grid->cursor.point.col, term->cols - 1));
+
+            tll_free(term->alt.scroll_damage);
+
+            /* Delete all sixel images on the alt screen */
+            tll_foreach(term->alt.sixel_images, it) {
+                sixel_destroy(&it->item);
+                tll_remove(term->alt.sixel_images, it);
+            }
+
+            term_damage_all(term);
+        }
+        break;
+
+    case 2004:
+        term->bracketed_paste = enable;
+        break;
+
+    default:
+        UNHANDLED();
+        break;
+    }
+}
+
+static void
+decset(struct terminal *term, unsigned param)
+{
+    decset_decrst(term, param, true);
+}
+
+static void
+decrst(struct terminal *term, unsigned param)
+{
+    deecset_decrst(term, param, false);
+}
+
 void
 csi_dispatch(struct terminal *term, uint8_t final)
 {
@@ -1008,283 +1206,17 @@ csi_dispatch(struct terminal *term, uint8_t final)
 
     case '?': {
         switch (final) {
-        case 'h': {
-            for (size_t i = 0; i < term->vt.params.idx; i++) {
-                switch (term->vt.params.v[i].value) {
-                case 1:
-                    term->cursor_keys_mode = CURSOR_KEYS_APPLICATION;
-                    break;
-
-                case 3:
-                    LOG_WARN("unimplemented: 132 column mode (DECCOLM, %s)",
-                             csi_as_string(term, final, i));
-                    term_erase(
-                        term,
-                        &(struct coord){0, 0},
-                        &(struct coord){term->cols - 1, term->rows - 1});
-                    term_cursor_home(term);
-                    break;
-
-                case 4:
-                    /* DECSCLM - Smooth scroll */
-                    LOG_WARN("unimplemented: Smooth (Slow) Scroll (DECSCLM, %s)",
-                             csi_as_string(term, final, i));
-                    break;
-
-                case 5:
-                    term->reverse = true;
-                    term_damage_all(term);
-                    break;
-
-                case 6: { /* DECOM */
-                    term->origin = ORIGIN_RELATIVE;
-                    term_cursor_home(term);
-                    break;
-                }
-
-                case 7:
-                    /* DECAWM */
-                    term->auto_margin = true;
-                    term->grid->cursor.lcf = false;
-                    break;
-
-                case 9:
-                    LOG_WARN("unimplemented: X10 mouse tracking mode");
-                    /* term->mouse_tracking = MOUSE_X10; */
-                    break;
-
-                case 12:
-                    term_cursor_blink_enable(term);
-                    break;
-
-                case 25:
-                    term->hide_cursor = false;
-                    break;
-
-                case 1000:
-                    term->mouse_tracking = MOUSE_CLICK;
-                    term_xcursor_update(term);
-                    break;
-
-                case 1001:
-                    LOG_WARN("unimplemented: highlight mouse tracking");
-                    break;
-
-                case 1002:
-                    term->mouse_tracking = MOUSE_DRAG;
-                    term_xcursor_update(term);
-                    break;
-
-                case 1003:
-                    term->mouse_tracking = MOUSE_MOTION;
-                    term_xcursor_update(term);
-                    break;
-
-                case 1004:
-                    term->focus_events = true;
-                    break;
-
-                case 1005:
-                    LOG_WARN("unimplemented: mouse reporting mode: UTF-8");
-                    /* term->mouse_reporting = MOUSE_UTF8; */
-                    break;
-
-                case 1006:
-                    LOG_DBG("mouse reporting mode: SGR");
-                    term->mouse_reporting = MOUSE_SGR;
-                    break;
-
-                case 1007:
-                    term->alt_scrolling = true;
-                    break;
-
-                case 1015:
-                    LOG_DBG("mouse reporting mode: urxvt");
-                    term->mouse_reporting = MOUSE_URXVT;
-                    break;
-
-                case 1034:
-                    /* smm */
-                    LOG_DBG("enabling 8-bit meta mode");
-                    term->meta.eight_bit = true;
-                    break;
-
-                case 1036:
-                    /* metaSendsEscape */
-                    LOG_DBG("enabling meta-sends-escape");
-                    term->meta.esc_prefix = true;
-                    break;
-
-#if 0
-                case 1042:
-                    LOG_WARN("unimplemented: 'urgency' window manager hint on ctrl-g");
-                    break;
-
-                case 1043:
-                    LOG_WARN("unimplemented: raise window on ctrl-g");
-                    break;
-#endif
-
-                case 1049:
-                    if (term->grid != &term->alt) {
-                        selection_cancel(term);
-
-                        term->grid = &term->alt;
-
-                        term_cursor_to(
-                            term,
-                            min(term->grid->cursor.point.row, term->rows - 1),
-                            min(term->grid->cursor.point.col, term->cols - 1));
-
-                        tll_free(term->alt.scroll_damage);
-
-                        term_erase(
-                            term,
-                            &(struct coord){0, 0},
-                            &(struct coord){term->cols - 1, term->rows - 1});
-                    }
-                    break;
-
-                case 2004:
-                    term->bracketed_paste = true;
-                    break;
-
-                default:
-                    UNHANDLED();
-                    break;
-                }
-            }
+        case 'h':
+            /* DECSET - DEC private mode set */
+            for (size_t i = 0; i < term->vt.params.idx; i++)
+                decset(term, term->vt.params.v[i].value);
             break;
-        }
 
-        case 'l': {
-            for (size_t i = 0; i < term->vt.params.idx; i++) {
-                switch (term->vt.params.v[i].value) {
-                case 1:
-                    term->cursor_keys_mode = CURSOR_KEYS_NORMAL;
-                    break;
-
-                case 3:
-                    /* DECCOLM - 80 column mode */
-                    term_erase(
-                        term,
-                        &(struct coord){0, 0},
-                        &(struct coord){term->cols - 1, term->rows - 1});
-                    term_cursor_home(term);
-                    break;
-
-                case 4:
-                    /* DECSCLM - Jump scroll */
-                    break;
-
-                case 5:
-                    term->reverse = false;
-                    term_damage_all(term);
-                    break;
-
-                case 6: { /* DECOM */
-                    term->origin = ORIGIN_ABSOLUTE;
-                    term_cursor_home(term);
-                    break;
-                }
-
-                case 7:
-                    /* DECAWM */
-                    term->auto_margin = false;
-                    term->grid->cursor.lcf = false;
-                    break;
-
-                case 12:
-                    term_cursor_blink_disable(term);
-                    break;
-
-                case 25:
-                    term->hide_cursor = true;
-                    break;
-
-                case 1001:
-                    /* Highlight mouse tracking */
-                    break;
-
-                case 9:     /* MOUSE_X10 */
-                case 1000:  /* MOUSE_NORMAL */
-                case 1002:  /* MOUSE_BUTTON_EVENT */
-                case 1003:  /* MOUSE_ANY_EVENT */
-                    term->mouse_tracking = MOUSE_NONE;
-                    term_xcursor_update(term);
-                    break;
-
-                case 1005:  /* MOUSE_UTF8 */
-                case 1006:  /* MOUSE_SGR */
-                case 1015:  /* MOUSE_URXVT */
-                    LOG_DBG("mouse reporting mode: legacy");
-                    term->mouse_reporting = MOUSE_NORMAL;
-                    break;
-
-                case 1004:
-                    term->focus_events = false;
-                    break;
-
-                case 1007:
-                    term->alt_scrolling = false;
-                    break;
-
-                case 1034:
-                    /* rmm */
-                    LOG_DBG("disabling 8-bit meta mode");
-                    term->meta.eight_bit = false;
-                    break;
-
-                case 1036:
-                    /* metaSendsEscape */
-                    LOG_DBG("disabling  meta-sends-escape");
-                    term->meta.esc_prefix = false;
-                    break;
-
-#if 0
-                case 1042:
-                    /* 'urgency' window manager hint on ctrl-g */
-                    break;
-
-                case 1043:
-                    /* raise window on ctrl-g */
-                    break;
-#endif
-
-                case 1049:
-                    if (term->grid == &term->alt) {
-                        selection_cancel(term);
-
-                        term->grid = &term->normal;
-
-                        term_cursor_to(
-                            term,
-                            min(term->grid->cursor.point.row, term->rows - 1),
-                            min(term->grid->cursor.point.col, term->cols - 1));
-
-                        tll_free(term->alt.scroll_damage);
-
-                        /* Delete all sixel images on the alt screen */
-                        tll_foreach(term->alt.sixel_images, it) {
-                            sixel_destroy(&it->item);
-                            tll_remove(term->alt.sixel_images, it);
-                        }
-
-                        term_damage_all(term);
-                    }
-                    break;
-
-                case 2004:
-                    term->bracketed_paste = false;
-                    break;
-
-                default:
-                    UNHANDLED();
-                    break;
-                }
-            }
+        case 'l':
+            /* DECRST - DEC private mode reset */
+            for (size_t i = 0; i < term->vt.params.idx; i++)
+                decrst(term, term->vt.params.v[i].value);
             break;
-        }
 
         case 'p': {
             if (term->vt.private[1] != '$') {