diff --git a/generic.rkt b/generic.rkt
index 2385937..0571235 100644
--- a/generic.rkt
+++ b/generic.rkt
@@ -77,10 +77,18 @@
 ;;; A poor man's fallback for dds-step-one-annotated.
 (define (fallback-dds-step-one-annotated dds s) (dds-step-one-annotated dds s))
 
+;;; Run dds-step-one-annotated, but then discard the annotations.
+;;; This is a fallback for dds-step-one.
+(define (fallback-dds-step-one dds state)
+  (for/set ([annotation-state (dds-step-one-annotated dds state)])
+    (match annotation-state
+      [(cons a s) s])))
+
 ;;; A discrete dynamical system.
 (define-generics dds
   ;; Given a dds and a state, produce the next states of the dds.
-  ;; This method has no fallback.
+  ;; This method falls back to calling dds-step-one-annotated,
+  ;; discarding the annotations.
   (dds-step-one dds state)
   ;; Given a dds and a state, produce the next states paired with some
   ;; annotation.  Typical usage would include including the
@@ -113,6 +121,7 @@
   #:defined-predicate dds-implements?
   #:fallbacks
   [(define dds-step fallback-dds-step)
+   (define dds-step-one fallback-dds-step-one)
 
    ;; Run fallback-dds-build-state-graph-edges with an infinite range,
    ;; which will make it stop only when it has explored all the state