diff --git a/UnitClasses/HealableUnit.cpp b/UnitClasses/HealableUnit.cpp
index 65a5c91..c50b46f 100644
--- a/UnitClasses/HealableUnit.cpp
+++ b/UnitClasses/HealableUnit.cpp
@@ -2,7 +2,7 @@
 #include "../Game.h"
 
 HealableUnit::HealableUnit(Game* gamePtr, UnitType unitType, double health, int power, int attackCapacity)
-    : Unit(gamePtr, unitType, health, power, attackCapacity), UMLjoinTime(0)
+    : Unit(gamePtr, unitType, health, power, attackCapacity), UMLjoinTime(-1)
 {}
 
 bool HealableUnit::needsHeal() const
@@ -22,6 +22,11 @@ bool HealableUnit::isHealed() const
     return health > initialHealth * 0.2;
 }
 
+bool HealableUnit::hasBeenInUMLbefore() const
+{
+    return UMLjoinTime != -1;
+}
+
 void HealableUnit::receiveHeal(double UHP)
 {
     // Infected units get twice the time to get healed
@@ -33,5 +38,7 @@ void HealableUnit::receiveHeal(double UHP)
 
 void HealableUnit::setUMLjoinTime(int UMLjoinTime)
 {
-    this->UMLjoinTime = UMLjoinTime;
-}
\ No newline at end of file
+    // Check if it's the unit first time to join uml 
+    if (!hasBeenInUMLbefore())
+        this->UMLjoinTime = UMLjoinTime;
+}
diff --git a/UnitClasses/HealableUnit.h b/UnitClasses/HealableUnit.h
index 0be24c3..cf2c020 100644
--- a/UnitClasses/HealableUnit.h
+++ b/UnitClasses/HealableUnit.h
@@ -17,6 +17,7 @@ class HealableUnit: public Unit
     bool needsHeal() const; // Check if the unit is eligible for healing
     bool hasWaitedForTooLong() const; // Decides whether to kill or heal the unit based on its wait time
     bool isHealed() const; // Checks if the unit's health has increased enough
+    bool hasBeenInUMLbefore() const; // Check if it has been inside uml before or not
 
     void receiveHeal(double); // Increase the health of the unit by "UHP"