diff --git a/src/hyperloglog.c b/src/hyperloglog.c
index a2d5ff2d7..a8f7ebd13 100644
--- a/src/hyperloglog.c
+++ b/src/hyperloglog.c
@@ -662,12 +662,22 @@ int hllSparseSet(robj *o, long index, uint8_t count) {
      * switch to dense representation. */
     if (count > HLL_SPARSE_VAL_MAX_VALUE) goto promote;
 
-    /* When updating a sparse representation, sometimes we may need to
-     * enlarge the buffer for up to 3 bytes in the worst case (XZERO split
-     * into XZERO-VAL-XZERO). Make sure there is enough space right now
-     * so that the pointers we take during the execution of the function
-     * will be valid all the time. */
-    o->ptr = sdsMakeRoomFor(o->ptr,3);
+    /* When updating a sparse representation, sometimes we may need to enlarge the
+     * buffer for up to 3 bytes in the worst case (XZERO split into XZERO-VAL-XZERO),
+     * and the following code does the enlarge job.
+     * Actually, we use a greedy strategy, enlarge more than 3 bytes to avoid the need
+     * for future reallocates on incremental growth. But we do not allocate more than
+     * 'server.hll_sparse_max_bytes' bytes for the sparse representation.
+     * If the available size of hyperloglog sds string is not enough for the increment
+     * we need, we promote the hypreloglog to dense representation in 'step 3'.
+     */
+    if (sdsalloc(o->ptr) < server.hll_sparse_max_bytes && sdsavail(o->ptr) < 3) {
+        size_t newlen = sdslen(o->ptr) + 3;
+        newlen += min(newlen, 300); /* Greediness: double 'newlen' if it is smaller than 300, or add 300 to it when it exceeds 300 */
+        if (newlen > server.hll_sparse_max_bytes)
+            newlen = server.hll_sparse_max_bytes;
+        o->ptr = sdsResize(o->ptr, newlen);
+    }
 
     /* Step 1: we need to locate the opcode we need to modify to check
      * if a value update is actually needed. */
@@ -824,17 +834,18 @@ int hllSparseSet(robj *o, long index, uint8_t count) {
     /* Step 3: substitute the new sequence with the old one.
      *
      * Note that we already allocated space on the sds string
-     * calling sdsMakeRoomFor(). */
-     int seqlen = n-seq;
-     int oldlen = is_xzero ? 2 : 1;
-     int deltalen = seqlen-oldlen;
+     * calling sdsResize(). */
+    int seqlen = n-seq;
+    int oldlen = is_xzero ? 2 : 1;
+    int deltalen = seqlen-oldlen;
 
-     if (deltalen > 0 &&
-         sdslen(o->ptr)+deltalen > server.hll_sparse_max_bytes) goto promote;
-     if (deltalen && next) memmove(next+deltalen,next,end-next);
-     sdsIncrLen(o->ptr,deltalen);
-     memcpy(p,seq,seqlen);
-     end += deltalen;
+    if (deltalen > 0 &&
+        sdslen(o->ptr) + deltalen > server.hll_sparse_max_bytes) goto promote;
+    serverAssert(sdslen(o->ptr) + deltalen <= sdsalloc(o->ptr));
+    if (deltalen && next) memmove(next+deltalen,next,end-next);
+    sdsIncrLen(o->ptr,deltalen);
+    memcpy(p,seq,seqlen);
+    end += deltalen;
 
 updated:
     /* Step 4: Merge adjacent values if possible.
diff --git a/tests/unit/hyperloglog.tcl b/tests/unit/hyperloglog.tcl
index 0103b2ab9..ee437189f 100644
--- a/tests/unit/hyperloglog.tcl
+++ b/tests/unit/hyperloglog.tcl
@@ -59,6 +59,36 @@ start_server {tags {"hll"}} {
         }
     } {} {needs:pfdebug}
 
+    test {Change hll-sparse-max-bytes} {
+        r config set hll-sparse-max-bytes 3000
+        r del hll
+        r pfadd hll a b c d e d g h i j k
+        assert {[r pfdebug encoding hll] eq {sparse}}
+        r config set hll-sparse-max-bytes 30
+        r pfadd hll new_element
+        assert {[r pfdebug encoding hll] eq {dense}}
+    } {} {needs:pfdebug}
+
+    test {Hyperloglog promote to dense well in different hll-sparse-max-bytes} {
+        set max(0) 100
+        set max(1) 500
+        set max(2) 3000
+        for {set i 0} {$i < [array size max]} {incr i} {
+            r config set hll-sparse-max-bytes $max($i)
+            r del hll
+            r pfadd hll
+            set len [r strlen hll]
+            while {$len <= $max($i)} {
+                assert {[r pfdebug encoding hll] eq {sparse}}
+                set elements {}
+                for {set j 0} {$j < 10} {incr j} { lappend elements [expr rand()]}
+                r pfadd hll {*}$elements
+                set len [r strlen hll]
+            }
+            assert {[r pfdebug encoding hll] eq {dense}}
+        }
+    } {} {needs:pfdebug}
+
     test {HyperLogLog sparse encoding stress test} {
         for {set x 0} {$x < 1000} {incr x} {
             r del hll1