diff --git a/collects/mred/mred-sig.ss b/collects/mred/mred-sig.ss
index e24a6554..a2933039 100644
--- a/collects/mred/mred-sig.ss
+++ b/collects/mred/mred-sig.ss
@@ -94,6 +94,7 @@
      grow-box-spacer-pane%
      horizontal-pane%
      horizontal-panel%
+     tab-panel%
      image-snip%
      is-busy?
      is-color-display?