diff --git a/src/string.c b/src/string.c
index 14f6433c4..085c2daa2 100644
--- a/src/string.c
+++ b/src/string.c
@@ -340,7 +340,7 @@ chars2bytes(mrb_value s, mrb_int off, mrb_int idx)
   }
 
   mrb_int len = (mrb_int)(p-p0);
-  if (idx > 0 || p > e) len++;
+  if (idx > 0) len++;
   return len;
 }