diff --git a/src/Redis/Lua/LuaExtension.php b/src/Redis/Lua/LuaExtension.php
index 04f3512..dd951a6 100644
--- a/src/Redis/Lua/LuaExtension.php
+++ b/src/Redis/Lua/LuaExtension.php
@@ -10,8 +10,6 @@ abstract class LuaExtension {
     public function __construct(\Redis $redis)
     {
         $this->redis = $redis;
-
-        $this->load();
     }
 
     public function getFunctionNames() : array {
@@ -25,7 +23,7 @@ abstract class LuaExtension {
         return $this->hash;
     }
 
-    protected function load(){
+    public function load(){
         if(!$this->hash){
             $exists = $this->redis->script('exists', $this->getScript());
             if(!$exists[0]){
diff --git a/src/Redis/Lua/SetIfLower.php b/src/Redis/Lua/SetIfLower.php
new file mode 100644
index 0000000..4a5631e
--- /dev/null
+++ b/src/Redis/Lua/SetIfLower.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Benzine\Redis\Lua;
+
+class SetIfLower extends LuaExtension
+{
+    protected function getScript() : string
+    {
+        return <<<'LUA'
+                local c = tonumber(redis.call('get', KEYS[1])); 
+                if c then 
+                    if tonumber(ARGV[1]) < c then 
+                        redis.call('set', KEYS[1], ARGV[1]) 
+                        return tonumber(ARGV[1]) - c 
+                    else 
+                        return 0 
+                    end 
+                else 
+                    return redis.call('set', KEYS[1], ARGV[1]) 
+                end
+            LUA;
+    }
+}
diff --git a/src/Redis/Lua/ZAddIfHigher.php b/src/Redis/Lua/ZAddIfHigher.php
new file mode 100644
index 0000000..725d5b9
--- /dev/null
+++ b/src/Redis/Lua/ZAddIfHigher.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Benzine\Redis\Lua;
+
+class ZAddIfHigher extends LuaExtension
+{
+    protected function getScript() : string
+    {
+        return <<<'LUA'
+                local c = tonumber(redis.call('zscore', KEYS[1], ARGV[1])); 
+                if c then  
+                    if tonumber(KEYS[2]) > c then 
+                        redis.call('zadd', KEYS[1], KEYS[2], ARGV[1]) 
+                        return tonumber(KEYS[2]) - c 
+                    else 
+                        return 0
+                    end 
+                else 
+                    redis.call('zadd', KEYS[1], KEYS[2], ARGV[1]) 
+                    return 'OK' 
+                end
+            LUA;
+    }
+}
diff --git a/src/Redis/Lua/ZAddIfLower.php b/src/Redis/Lua/ZAddIfLower.php
new file mode 100644
index 0000000..c7f126d
--- /dev/null
+++ b/src/Redis/Lua/ZAddIfLower.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Benzine\Redis\Lua;
+
+class ZAddIfLower extends LuaExtension
+{
+    protected function getScript() : string
+    {
+        return <<<'LUA'
+                local c = tonumber(redis.call('zscore', KEYS[1], ARGV[1])); 
+                if c then  
+                    if tonumber(KEYS[2]) < c then 
+                        redis.call('zadd', KEYS[1], KEYS[2], ARGV[1]) 
+                        return tonumber(KEYS[2]) - c 
+                    else 
+                        return 0
+                    end 
+                else 
+                    redis.call('zadd', KEYS[1], KEYS[2], ARGV[1]) 
+                    return 'OK' 
+                end
+            LUA;
+    }
+}
diff --git a/src/Redis/Redis.php b/src/Redis/Redis.php
index 2cfced4..85b8241 100644
--- a/src/Redis/Redis.php
+++ b/src/Redis/Redis.php
@@ -11,6 +11,9 @@ class Redis extends \Redis
     public function initialiseExtensions() : void
     {
         $this->scripts[] = new Lua\SetIfHigher($this);
+        $this->scripts[] = new Lua\SetIfLower($this);
+        $this->scripts[] = new Lua\ZAddIfHigher($this);
+        $this->scripts[] = new Lua\ZAddIfLower($this);
     }
     
     public function connect($host, $port = 6379, $timeout = 0.0, $reserved = null, $retryInterval = 0, $readTimeout = 0.0)
@@ -24,6 +27,7 @@ class Redis extends \Redis
         foreach($this->scripts as $script){
             foreach($script->getFunctionNames() as $functionName){
                 if(strtolower($name) == strtolower($functionName)){
+                    $script->load();
                     return $this->evalSha($script->getHash(), $arguments);
                 }
             }