diff --git a/ringbuf.c b/ringbuf.c
index 9c57e68..375b5d5 100644
--- a/ringbuf.c
+++ b/ringbuf.c
@@ -15,7 +15,7 @@ void rb_destroy(struct RingBuf *rb, int(free)(void *)) { free(rb->buffer); }
 
 enum WriteResult rb_push(struct RingBuf *rb, void *data[], int amount,
                          int (*memcpy)(void *, const void *, int)) {
-  if (rb->write_idx == rb->read_idx) {
+  if (rb->write_idx + amount >= rb->capacity) {
     return CollisionError;
   }