diff --git a/src/vm.c b/src/vm.c
index 3ed498405..2d0f9ee98 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -2774,6 +2774,7 @@ RETRY_TRY_BLOCK:
     CASE(OP_STRCAT, B) {
       mrb_assert(mrb_string_p(regs[a]));
       mrb_str_concat(mrb, regs[a], regs[a+1]);
+      ci = mrb->c->ci;
       NEXT;
     }