diff --git a/pkgs/racket-test-core/tests/racket/optimize.rktl b/pkgs/racket-test-core/tests/racket/optimize.rktl
index 01ab2b1f16..df465a98f8 100644
--- a/pkgs/racket-test-core/tests/racket/optimize.rktl
+++ b/pkgs/racket-test-core/tests/racket/optimize.rktl
@@ -3629,6 +3629,30 @@
               (set! f 0))
            #f)
 
+;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Check that the type information is shifted in the
+;; right direction while inlining.
+;; The first example triggered a bug in 6.3.
+
+(test-comp '(let ([zz (lambda (x) (lambda (y) 0))])
+              (lambda (a b c)
+                ((zz (let ([loop (lambda () 0)]) loop)) (car a))
+                (list c (pair? c))))
+           '(let ([zz (lambda (x) (lambda (y) 0))])
+              (lambda (a b c)
+                ((zz (let ([loop (lambda () 0)]) loop)) (car a))
+                (list c #t)))
+           #f)
+
+(test-comp '(let ([zz (lambda (x) (lambda (y) 0))])
+              (lambda (a b c)
+                ((zz (let ([loop (lambda () 0)]) loop)) (car a))
+                (list a (pair? a))))
+           '(let ([zz (lambda (x) (lambda (y) 0))])
+              (lambda (a b c)
+                ((zz (let ([loop (lambda () 0)]) loop)) (car a))
+                (list a #t))))
+
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; Check that the unused continuations are removed
 
@@ -4179,9 +4203,9 @@
     (test-values '(-100001.0t0 100001.0t0) tail)))
 
 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-;; Check for corect fixpoint calculation when lifting
+;; Check for correct fixpoint calculation when lifting
 
-;; This test is especilly fragile. It's a minimized(?) variant
+;; This test is especially fragile. It's a minimized(?) variant
 ;; of PR 12910, where just enbought `with-continuation-mark's
 ;; are needed to thwart inlining, and enough functions are 
 ;; present in the right order to require enough fixpoint
diff --git a/racket/src/racket/src/optimize.c b/racket/src/racket/src/optimize.c
index 3d700107e2..11cf2f1ac5 100644
--- a/racket/src/racket/src/optimize.c
+++ b/racket/src/racket/src/optimize.c
@@ -1959,7 +1959,7 @@ Scheme_Object *optimize_for_inline(Optimize_Info *info, Scheme_Object *le, int a
                              id_offset, orig_le, prev);
           if (id_offset) {
             optimize_info_done(sub_info, NULL);
-            merge_types(sub_info, info, id_offset);
+            merge_types(sub_info, info, -id_offset);
           }
           return le;
 	} else {
@@ -5922,7 +5922,7 @@ scheme_optimize_lets(Scheme_Object *form, Optimize_Info *info, int for_inline, i
             info->single_result = sub_info->single_result;
             info->preserves_marks = sub_info->preserves_marks;
             optimize_info_done(sub_info, NULL);
-            merge_types(sub_info, info, 1);
+            merge_types(sub_info, info, -1);
           }
 
           return form;
@@ -5948,7 +5948,7 @@ scheme_optimize_lets(Scheme_Object *form, Optimize_Info *info, int for_inline, i
           info->single_result = sub_info->single_result;
           info->preserves_marks = sub_info->preserves_marks;
           optimize_info_done(sub_info, NULL);
-          merge_types(sub_info, info, 1);
+          merge_types(sub_info, info, -1);
           return body;
 	}
       }