diff --git a/src/server.h b/src/server.h
index c34cdcfbf..f5089438d 100644
--- a/src/server.h
+++ b/src/server.h
@@ -339,7 +339,7 @@ typedef long long mstime_t; /* millisecond time type. */
 /* Anti-warning macro... */
 #define UNUSED(V) ((void) V)
 
-#define ZSKIPLIST_MAXLEVEL 32 /* Should be enough for 2^32 elements */
+#define ZSKIPLIST_MAXLEVEL 64 /* Should be enough for 2^64 elements */
 #define ZSKIPLIST_P 0.25      /* Skiplist P = 1/4 */
 
 /* Append only defines */
@@ -782,7 +782,7 @@ typedef struct zskiplistNode {
     struct zskiplistNode *backward;
     struct zskiplistLevel {
         struct zskiplistNode *forward;
-        unsigned int span;
+        unsigned long span;
     } level[];
 } zskiplistNode;
 
@@ -1628,7 +1628,7 @@ void zzlNext(unsigned char *zl, unsigned char **eptr, unsigned char **sptr);
 void zzlPrev(unsigned char *zl, unsigned char **eptr, unsigned char **sptr);
 unsigned char *zzlFirstInRange(unsigned char *zl, zrangespec *range);
 unsigned char *zzlLastInRange(unsigned char *zl, zrangespec *range);
-unsigned int zsetLength(const robj *zobj);
+unsigned long zsetLength(const robj *zobj);
 void zsetConvert(robj *zobj, int encoding);
 void zsetConvertToZiplistIfNeeded(robj *zobj, size_t maxelelen);
 int zsetScore(robj *zobj, sds member, double *score);
diff --git a/src/t_zset.c b/src/t_zset.c
index 196864779..1322e7d35 100644
--- a/src/t_zset.c
+++ b/src/t_zset.c
@@ -1100,8 +1100,8 @@ unsigned char *zzlDeleteRangeByRank(unsigned char *zl, unsigned int start, unsig
  * Common sorted set API
  *----------------------------------------------------------------------------*/
 
-unsigned int zsetLength(const robj *zobj) {
-    int length = -1;
+unsigned long zsetLength(const robj *zobj) {
+    unsigned long length = 0;
     if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
         length = zzlLength(zobj->ptr);
     } else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
@@ -1878,7 +1878,7 @@ void zuiClearIterator(zsetopsrc *op) {
     }
 }
 
-int zuiLength(zsetopsrc *op) {
+unsigned long zuiLength(zsetopsrc *op) {
     if (op->subject == NULL)
         return 0;
 
@@ -2085,7 +2085,11 @@ int zuiFind(zsetopsrc *op, zsetopval *val, double *score) {
 }
 
 int zuiCompareByCardinality(const void *s1, const void *s2) {
-    return zuiLength((zsetopsrc*)s1) - zuiLength((zsetopsrc*)s2);
+    unsigned long first = zuiLength((zsetopsrc*)s1);
+    unsigned long second = zuiLength((zsetopsrc*)s2);
+    if (first > second) return 1;
+    if (first < second) return -1;
+    return 0;
 }
 
 #define REDIS_AGGR_SUM 1
@@ -2129,7 +2133,7 @@ void zunionInterGenericCommand(client *c, robj *dstkey, int op) {
     zsetopsrc *src;
     zsetopval zval;
     sds tmp;
-    unsigned int maxelelen = 0;
+    size_t maxelelen = 0;
     robj *dstobj;
     zset *dstzset;
     zskiplistNode *znode;
@@ -2363,8 +2367,8 @@ void zrangeGenericCommand(client *c, int reverse) {
     int withscores = 0;
     long start;
     long end;
-    int llen;
-    int rangelen;
+    long llen;
+    long rangelen;
 
     if ((getLongFromObjectOrReply(c, c->argv[2], &start, NULL) != C_OK) ||
         (getLongFromObjectOrReply(c, c->argv[3], &end, NULL) != C_OK)) return;
@@ -2671,7 +2675,7 @@ void zcountCommand(client *c) {
     robj *key = c->argv[1];
     robj *zobj;
     zrangespec range;
-    int count = 0;
+    unsigned long count = 0;
 
     /* Parse the range arguments */
     if (zslParseRange(c->argv[2],c->argv[3],&range) != C_OK) {
@@ -2748,7 +2752,7 @@ void zlexcountCommand(client *c) {
     robj *key = c->argv[1];
     robj *zobj;
     zlexrangespec range;
-    int count = 0;
+    unsigned long count = 0;
 
     /* Parse the range arguments */
     if (zslParseLexRange(c->argv[2],c->argv[3],&range) != C_OK) {