1 files changed, 11 insertions, 2 deletions
diff --git a/vm_dump.c b/vm_dump.c
index da2e6a951d..a0d8bcb4d1 100644
--- a/vm_dump.c
+++ b/vm_dump.c
@@ -1000,12 +1000,21 @@ rb_vm_bugreport(const void *ctx)
 	    else if (RB_TYPE_P(name, T_CLASS) || RB_TYPE_P(name, T_MODULE)) {
 		const char *const type = RB_TYPE_P(name, T_CLASS) ?
 		    "class" : "module";
-		name = rb_class_name(name);
+		name = rb_search_class_path(rb_class_real(name));
+		if (!RB_TYPE_P(name, T_STRING)) {
+		    fprintf(stderr, " %4d %s:<unnamed>\n", i, type);
+		    continue;
+		}
 		fprintf(stderr, " %4d %s:%.*s\n", i, type,
 			LIMITED_NAME_LENGTH(name), RSTRING_PTR(name));
 	    }
 	    else {
-		VALUE klass = rb_class_name(CLASS_OF(name));
+		VALUE klass = rb_search_class_path(rb_obj_class(name));
+		if (!RB_TYPE_P(klass, T_STRING)) {
+		    fprintf(stderr, " %4d #<%p:%p>\n", i,
+			    (void *)CLASS_OF(name), (void *)name);
+		    continue;
+		}
 		fprintf(stderr, " %4d #<%.*s:%p>\n", i,
 			LIMITED_NAME_LENGTH(klass), RSTRING_PTR(klass),
 			(void *)name);