diff --git a/object.c b/object.c
index 86468ca4e1..4610070a3c 100644
--- a/object.c
+++ b/object.c
@@ -2579,7 +2579,7 @@ static VALUE
 convert_type(VALUE val, const char *tname, const char *method, int raise)
 {
     ID m = 0;
-    int i;
+    int i = numberof(conv_method_names);
     VALUE r;
     static const char prefix[] = "to_";