diff --git a/miner.lua b/miner.lua
index 41705c9..f4e9cd2 100644
--- a/miner.lua
+++ b/miner.lua
@@ -37,8 +37,8 @@ local function isOdd(x)
 end
 
 local function checkConfig()
-  if config.targetY > config.startY then
-    error('targetY cannot be higher that startY')
+  if config.targetY >= config.startY then
+    error('targetY should be lower than startY')
   end
 
   if config.height < 1 then