diff --git a/ringbuf.c b/ringbuf.c
index d73affe..ffc979e 100644
--- a/ringbuf.c
+++ b/ringbuf.c
@@ -29,7 +29,18 @@ rb_init(struct RingBuf *rb, rb_size_t capacity, ALLOC_T malloc_fn,
 void
 rb_destroy(struct RingBuf *rb, FREE_T free_fn)
 {
-  free_fn(rb->buffer);
+  if(rb->buffer) { // Prevent double-free
+    free_fn(rb->buffer);
+    rb->buffer = NULL;
+    rb->buffer_end = NULL;
+
+    rb->struct_size = 0;
+    rb->capacity = 0;
+    rb->count = 0;
+
+    rb->write_head = NULL;
+    rb->read_head = NULL;
+  }
 }
 
 void
@@ -46,6 +57,8 @@ rb_push_back(struct RingBuf *rb, const void *item, MEMCPY_T memcpy_fn)
   if(rb->count == rb->capacity)
     return Full;
 
+  assert(rb->buffer != NULL);
+
   memcpy_fn(rb->write_head, item, rb->struct_size);
 
   // Advance the write head