diff --git a/00-RELEASENOTES b/00-RELEASENOTES
index 2b67732a1..1d5486ae8 100644
--- a/00-RELEASENOTES
+++ b/00-RELEASENOTES
@@ -11,6 +11,34 @@ CRITICAL: There is a critical bug affecting MOST USERS. Upgrade ASAP.
 SECURITY: There are security fixes in the release.
 --------------------------------------------------------------------------------
 
+================================================================================
+Redis 6.0.1     Released Sat May 02 00:06:07 CEST 2020
+================================================================================
+
+Upgrade urgency HIGH: This release fixes a crash when builiding against
+                      Libc malloc.
+
+Here we revert 8110ba888, an optimization that causes a crash due to a
+bug in the code. It does not happen with the default allocator because of
+differences between Jemalloc and libc malloc, so this escaped all our
+testing but was reported by a user. We'll add back the original optimization
+that was reverted here later, after checking what happens: it is not a
+critical optimization.
+
+The other commits are minor stuff:
+
+antirez in commit db73d0998:
+ Cast printf() argument to the format specifier.
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+antirez in commit 7c0fe7271:
+ Revert "optimize memory usage of deferred replies"
+ 1 file changed, 31 deletions(-)
+
+antirez in commit 8fe25edc7:
+ Save a call to stopThreadedIOIfNeeded() for the base case.
+ 1 file changed, 3 insertions(+), 3 deletions(-)
+
 ================================================================================
 Redis 6.0.0 GA  Released Thu Apr 30 14:55:02 CEST 2020
 ================================================================================
diff --git a/src/networking.cpp b/src/networking.cpp
index ae4e4b765..caced9b32 100644
--- a/src/networking.cpp
+++ b/src/networking.cpp
@@ -566,36 +566,6 @@ void addReplyStatusFormat(client *c, const char *fmt, ...) {
     sdsfree(s);
 }
 
-/* Sometimes we are forced to create a new reply node, and we can't append to
- * the previous one, when that happens, we wanna try to trim the unused space
- * at the end of the last reply node which we won't use anymore. */
-void trimReplyUnusedTailSpace(client *c) {
-    listNode *ln = listLast(c->reply);
-    clientReplyBlock *tail = ln? (clientReplyBlock*)listNodeValue(ln): nullptr;
-
-    /* Note that 'tail' may be NULL even if we have a tail node, becuase when
-     * addDeferredMultiBulkLength() is used */
-    if (!tail) return;
-
-    /* We only try to trim the space is relatively high (more than a 1/4 of the
-     * allocation), otherwise there's a high chance realloc will NOP.
-     * Also, to avoid large memmove which happens as part of realloc, we only do
-     * that if the used part is small.  */
-    if (tail->size - tail->used > tail->size / 4 &&
-        tail->used < PROTO_REPLY_CHUNK_BYTES)
-    {
-        size_t old_size = tail->size;
-        tail = (clientReplyBlock*)zrealloc(tail, tail->used + sizeof(clientReplyBlock));
-        /* If realloc was a NOP, we got the same value which has internal frag */
-        if (tail == listNodeValue(ln)) return;
-        /* take over the allocation's internal fragmentation (at least for
-         * memory usage tracking) */
-        tail->size = zmalloc_usable(tail) - sizeof(clientReplyBlock);
-        c->reply_bytes += tail->size - old_size;
-        listNodeValue(ln) = tail;
-    }
-}
-
 /* Adds an empty object to the reply list that will contain the multi bulk
  * length, which is not known when this function is called. */
 void *addReplyDeferredLen(client *c) {
@@ -603,7 +573,6 @@ void *addReplyDeferredLen(client *c) {
      * ready to be sent, since we are sure that before returning to the
      * event loop setDeferredAggregateLen() will be called. */
     if (prepareClientToWrite(c, false) != C_OK) return NULL;
-    trimReplyUnusedTailSpace(c);
     listAddNodeTail(c->reply,NULL); /* NULL is our placeholder. */
     return listLast(c->reply);
 }
diff --git a/src/rdb.cpp b/src/rdb.cpp
index cb9714e40..ef61c92a9 100644
--- a/src/rdb.cpp
+++ b/src/rdb.cpp
@@ -2458,7 +2458,9 @@ int rdbLoadRio(rio *rdb, int rdbflags, rdbSaveInfo *rsi) {
                 serverLog(LL_WARNING,"RDB file was saved with checksum disabled: no check performed.");
             } else if (cksum != expected) {
                 serverLog(LL_WARNING,"Wrong RDB checksum expected: (%llx) but "
-                    "got (%llx). Aborting now.",expected,cksum);
+                    "got (%llx). Aborting now.",
+                        (unsigned long long)expected,
+                        (unsigned long long)cksum);
                 rdbExitReportCorruptRDB("RDB CRC error");
             }
         }