diff --git a/test/json/json_generator_test.rb b/test/json/json_generator_test.rb
index 00960dffee8d7f..0eb85a82653e7c 100755
--- a/test/json/json_generator_test.rb
+++ b/test/json/json_generator_test.rb
@@ -504,10 +504,14 @@ def to_s
       end
       alias_method :to_s, :to_s
     end
-    case RUBY_PLATFORM
-    when "java"
+    case RUBY_ENGINE
+    when "jruby"
       assert_equal bignum_to_s, JSON.generate(bignum)
-    else
+    when "truffleruby"
+      assert_raise(NoMethodError) do
+        JSON.generate(bignum)
+      end
+    when "ruby"
       assert_raise(TypeError) do
         JSON.generate(bignum)
       end
diff --git a/vm_dump.c b/vm_dump.c
index e2b4804ab0d583..4864ccf58bdb30 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -1435,8 +1435,11 @@ rb_vm_bugreport(const void *ctx, FILE *errout)
         kprintf("-- Threading information "
                 "---------------------------------------------------\n");
         kprintf("Total ractor count: %u\n", vm->ractor.cnt);
-        kprintf("Ruby thread count for this ractor: %u\n", rb_ec_ractor_ptr(ec)->threads.cnt);
-        if (ec->thread_ptr->scheduler != Qnil) {
+        const rb_ractor_t *cr = rb_ec_ractor_ptr(ec);
+        if (cr) {
+            kprintf("Ruby thread count for this ractor: %u\n", cr->threads.cnt);
+        }
+        if (ec->thread_ptr && ec->thread_ptr->scheduler != Qnil) {
             kprintf("Note that the Fiber scheduler is enabled\n");
         }
         kputs("\n");