1 files changed, 1 insertions, 1 deletions
diff --git a/vm.c b/vm.c
index 212d19b73b..786c94e5fa 100644
--- a/vm.c
+++ b/vm.c
@@ -150,7 +150,7 @@ env_alloc(void)
     return obj;
 }
 
-static VALUE check_env_value(VALUE envval);
+static VALUE check_env_value(const VALUE envval);
 
 static int
 check_env(rb_env_t * const env)