diff --git a/typed-racket-lib/typed-racket/optimizer/optimizer.rkt b/typed-racket-lib/typed-racket/optimizer/optimizer.rkt
index 3c59d790..a9074eb5 100644
--- a/typed-racket-lib/typed-racket/optimizer/optimizer.rkt
+++ b/typed-racket-lib/typed-racket/optimizer/optimizer.rkt
@@ -24,9 +24,9 @@
   (pattern opt:ignore-table^)
 
   ;; Can't optimize the body of this code because it isn't typechecked
-  (pattern (~and _:kw-lambda^
-             ((~and op let-values)
-              ([(i:id) e-rhs:opt-expr]) e-body:expr ...))
+  (pattern (~and (~or _:kw-lambda^ _:opt-lambda^)
+                 ((~and op let-values)
+                  ([(i:id) e-rhs:opt-expr]) e-body:expr ...))
            #:with opt (quasisyntax/loc/origin this-syntax #'op
                         (op ([(i) e-rhs.opt]) e-body ...)))
 
diff --git a/typed-racket-test/optimizer/tests/opt-arg.rkt b/typed-racket-test/optimizer/tests/opt-arg.rkt
new file mode 100644
index 00000000..8952c3b7
--- /dev/null
+++ b/typed-racket-test/optimizer/tests/opt-arg.rkt
@@ -0,0 +1,12 @@
+#lang typed/racket/base
+
+;; The optimizer now looks at all expressions regardless of shape (to log
+;; all expressions with type (Vectorof Float) as candidates for uses of
+;; flvectors).
+;; This revealed that, previously, the optimizer did not skip the generated
+;; body of optional arg function definitions (which is not typechecked, and so
+;; should be skipped). It did for kw arg functions, but not optional.
+;; This is now fixed, and this test is to guard against regressions.
+
+(define (slicef-at [force? #f])
+  #f)