diff --git a/scmvm/vm.scm b/scmvm/vm.scm
index 8b97898..7d7fa41 100644
--- a/scmvm/vm.scm
+++ b/scmvm/vm.scm
@@ -164,7 +164,7 @@
   (define ram-word-set! (cute vm-memory-set! vm <> <>))
   (define debugger (vm-debugger vm))
   (define exit? #f)
-  (define (jump x) (vm-pc-set! vm x))
+  (define (jump x) (vm-pc-set! vm (logand #x2fffffff x)))
   (define (fetch-byte)
     (let ([byte (ram-byte-ref (vm-pc vm))])
       (vm-pc-set! vm (+ (vm-pc vm) 1))