diff --git a/[core]/esx_lib/imports/timeout/shared.lua b/[core]/esx_lib/imports/timeout/shared.lua
index c68eec04..e684f3a4 100644
--- a/[core]/esx_lib/imports/timeout/shared.lua
+++ b/[core]/esx_lib/imports/timeout/shared.lua
@@ -7,6 +7,8 @@ local CancelledTimeouts = {}
 ---@param cb function
 ---@return number
 xLib.timeout.setTimeout = function(msec, cb)
+    xLib.verify(cb, "function", true)
+    
     local id <const> = TimeoutCount + 1
 
     SetTimeout(msec, function()
diff --git a/[core]/esx_lib/imports/waitFor/shared.lua b/[core]/esx_lib/imports/waitFor/shared.lua
index 31da0bfd..8202a1c6 100644
--- a/[core]/esx_lib/imports/waitFor/shared.lua
+++ b/[core]/esx_lib/imports/waitFor/shared.lua
@@ -10,13 +10,11 @@ xLib.waitFor = function(conditionFunc, errorMessage, timeoutMs)
         error("Timeout should be a positive number.")
     end
 
-    if not ESX.IsFunctionReference(conditionFunc) then
-        error("Condition Function should be a function reference.")
-    end
+    xLib.verify(conditionFunc, "function", true)
 
     -- since errorMessage is optional, we only validate it if the user provided it.
     if errorMessage then
-        ESX.AssertType(errorMessage, "string", "errorMessage should be a string.")
+        xLib.verify(errorMessage, "string", true)
     end
 
     local invokingResource = GetInvokingResource()