diff --git a/collects/scheme/private/class-internal.ss b/collects/scheme/private/class-internal.ss
index 89aa1857c7..97c9927d5d 100644
--- a/collects/scheme/private/class-internal.ss
+++ b/collects/scheme/private/class-internal.ss
@@ -2399,42 +2399,41 @@
       (if blame
           (apply raise-blame-error blame cls str args)
           (return #f)))
+    (define method-ht (class-method-ht cls))
+    (define beta-methods (class-beta-methods cls))
+    (define meth-flags (class-meth-flags cls))
+    (define (check-overrideable m)
+      (let ([index (hash-ref method-ht m #f)])
+        (unless index
+          (failed "no public method ~a" m))
+        (let ([flag (vector-ref meth-flags index)])
+          (when (eq? flag 'final)
+            (failed "method ~a is final, not overrideable" m))
+          (when (eq? flag 'augmentable)
+            (failed "method ~a is augmentable, not overrideable" m)))))
     (unless (class? cls)
       (failed "not a class"))
-    (let ([method-ht (class-method-ht cls)])
-      (for ([m (class/c-methods ctc)])
-        (unless (hash-ref method-ht m #f)
-          (failed "no public method ~a" m)))
-      (for ([m (class/c-overrides ctc)])
-        (let ([index (hash-ref method-ht m #f)])
-          (unless index
-            (failed "no public method ~a" m))
-          (let ([vec (vector-ref (class-beta-methods cls) index)])
-            (when (and (positive? (vector-length vec))
-                       (not (vector-ref vec (sub1 (vector-length vec)))))
-              (failed "method ~a is not overrideable" m)))))
-      (for ([m (class/c-augments ctc)])
-        (let ([index (hash-ref method-ht m #f)])
-          (unless index
-            (failed "no public method ~a" m))
-          (let ([vec (vector-ref (class-beta-methods cls) index)])
-            (when (zero? (vector-length vec))
-              (failed "method ~a has never been augmentable" m)))))
-      (for ([s (class/c-supers ctc)])
-        (let ([index (hash-ref method-ht s #f)])
-          (unless index
-            (failed "no public method ~a" s))
-          (let ([vec (vector-ref (class-beta-methods cls) index)])
-            (when (and (positive? (vector-length vec))
-                       (not (vector-ref vec (sub1 (vector-length vec)))))
-              (failed "method ~a is not overrideable" s)))))
-      (for ([i (class/c-inners ctc)])
-        (let ([index (hash-ref method-ht i #f)])
-          (unless index
-            (failed "no public method ~a" i))
-          (let* ([super (vector-ref (class-supers cls) (sub1 (class-pos cls)))])
-            (unless (eq? (vector-ref (class-meth-flags cls) index) 'augmentable)
-              (failed "method ~a is not augmentable" i))))))
+    (for ([m (class/c-methods ctc)])
+      (unless (hash-ref method-ht m #f)
+        (failed "no public method ~a" m)))
+    (for ([m (class/c-overrides ctc)])
+      (check-overrideable m))
+    (for ([m (class/c-augments ctc)])
+      (let ([index (hash-ref method-ht m #f)])
+        (unless index
+          (failed "no public method ~a" m))
+        (let ([vec (vector-ref beta-methods index)])
+          (when (zero? (vector-length vec))
+            (failed "method ~a has never been augmentable" m)))))
+    (for ([s (class/c-supers ctc)])
+      (check-overrideable s))
+    (for ([i (class/c-inners ctc)])
+      (let ([index (hash-ref method-ht i #f)])
+        (unless index
+          (failed "no public method ~a" i))
+        (let* ([super (vector-ref (class-supers cls) (sub1 (class-pos cls)))])
+          (unless (eq? (vector-ref meth-flags index) 'augmentable)
+            (failed "method ~a is not augmentable" i)))))
     (let ([field-ht (class-field-ht cls)])
       (for ([m (class/c-fields ctc)])
         (unless (hash-ref field-ht m #f)