Index: src/object.c
==================================================================
--- src/object.c
+++ src/object.c
@@ -91,10 +91,13 @@
 
 void*
 cfw_ref(void *ptr)
 {
 	CFWObject *obj = ptr;
+
+	if (obj == NULL)
+		return NULL;
 
 	obj->ref_cnt++;
 
 	return obj;
 }
@@ -101,19 +104,25 @@
 
 void
 cfw_unref(void *ptr)
 {
 	CFWObject *obj = ptr;
+
+	if (obj == NULL)
+		return NULL;
 
 	if (--obj->ref_cnt == 0)
 		cfw_free(obj);
 }
 
 void
 cfw_free(void *ptr)
 {
 	CFWObject *obj = ptr;
+
+	if (obj == NULL)
+		return NULL;
 
 	if (obj->cls->dtor != NULL)
 		obj->cls->dtor(obj);
 
 	free(obj);
@@ -121,26 +130,38 @@
 
 CFWClass*
 cfw_class(void *ptr)
 {
 	CFWObject *obj = ptr;
+
+	if (obj == NULL)
+		return NULL;
 
 	return obj->cls;
 }
 
 bool
 cfw_is(void *ptr, CFWClass *cls)
 {
 	CFWObject *obj = ptr;
+
+	if (obj == NULL || cls == NULL)
+		return false;
 
 	return (obj->cls == cls);
 }
 
 bool
 cfw_equal(void *ptr1, void *ptr2)
 {
 	CFWObject *obj1 = ptr1, *obj2 = ptr2;
+
+	if (obj1 == obj2)
+		return true;
+
+	if (obj1 == NULL || obj2 == NULL)
+		return false;
 
 	if (obj1->cls->equal != NULL) {
 		return obj1->cls->equal(obj1, obj2);
 	} else
 		return (obj1 == obj2);
@@ -148,10 +169,13 @@
 
 uint32_t
 cfw_hash(void *ptr)
 {
 	CFWObject *obj = ptr;
+
+	if (obj == NULL)
+		return 0;
 
 	if (obj->cls->hash != NULL)
 		return obj->cls->hash(obj);
 
 	return (uint32_t)(uintptr_t)ptr;
@@ -159,10 +183,13 @@
 
 void*
 cfw_copy(void *ptr)
 {
 	CFWObject *obj = ptr;
+
+	if (obj == NULL)
+		return NULL;
 
 	if (obj->cls->copy != NULL)
 		return obj->cls->copy(obj);
 
 	return NULL;