diff --git a/src/hyperloglog.c b/src/hyperloglog.c
index df79fc97..d4c0a48d 100644
--- a/src/hyperloglog.c
+++ b/src/hyperloglog.c
@@ -802,7 +802,7 @@ int hllSparseAdd(robj *o, unsigned char *ele, size_t elesize) {
      int deltalen = seqlen-oldlen;
 
      if (deltalen > 0 && sdslen(o->ptr)+deltalen > HLL_SPARSE_MAX) goto promote;
-     if (deltalen && next) memmove(next+deltalen,next,next-sparse);
+     if (deltalen && next) memmove(next+deltalen,next,end-next);
      sdsIncrLen(o->ptr,deltalen);
      memcpy(p,seq,seqlen);