diff --git a/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java b/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
index 4835bf1002..51b94e523e 100644
--- a/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
+++ b/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
@@ -505,7 +505,7 @@ public class NpcViewMod implements IBypassHandler
 				// bonus drop rate effect
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 			}
 			
diff --git a/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java b/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
index 28db8bde36..d6833be10e 100644
--- a/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
+++ b/L2J_Mobius_1.0_Ertheia/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
@@ -267,7 +267,7 @@ public class DropSearchBoard implements IParseBoardHandler
 						// bonus drop rate effect
 						if (dropRateEffectBonus > 0)
 						{
-							rateChance *= dropRateEffectBonus;
+							rateChance += rateChance * dropRateEffectBonus;
 						}
 					}
 					
diff --git a/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index 64052a9c58..2c8322ea65 100644
--- a/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_1.0_Ertheia/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -719,7 +719,7 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 				final double dropRateEffectBonus = killer.getStat().getValue(Stats.BONUS_DROP_RATE, 0);
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 				
 				// calculate if item will drop
diff --git a/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java b/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
index 4835bf1002..51b94e523e 100644
--- a/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
+++ b/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
@@ -505,7 +505,7 @@ public class NpcViewMod implements IBypassHandler
 				// bonus drop rate effect
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 			}
 			
diff --git a/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java b/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
index 28db8bde36..d6833be10e 100644
--- a/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
+++ b/L2J_Mobius_2.5_Underground/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
@@ -267,7 +267,7 @@ public class DropSearchBoard implements IParseBoardHandler
 						// bonus drop rate effect
 						if (dropRateEffectBonus > 0)
 						{
-							rateChance *= dropRateEffectBonus;
+							rateChance += rateChance * dropRateEffectBonus;
 						}
 					}
 					
diff --git a/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index 64052a9c58..2c8322ea65 100644
--- a/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_2.5_Underground/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -719,7 +719,7 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 				final double dropRateEffectBonus = killer.getStat().getValue(Stats.BONUS_DROP_RATE, 0);
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 				
 				// calculate if item will drop
diff --git a/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java b/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
index 4835bf1002..51b94e523e 100644
--- a/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
+++ b/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
@@ -505,7 +505,7 @@ public class NpcViewMod implements IBypassHandler
 				// bonus drop rate effect
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 			}
 			
diff --git a/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java b/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
index 28db8bde36..d6833be10e 100644
--- a/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
+++ b/L2J_Mobius_3.0_Helios/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
@@ -267,7 +267,7 @@ public class DropSearchBoard implements IParseBoardHandler
 						// bonus drop rate effect
 						if (dropRateEffectBonus > 0)
 						{
-							rateChance *= dropRateEffectBonus;
+							rateChance += rateChance * dropRateEffectBonus;
 						}
 					}
 					
diff --git a/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index 64052a9c58..2c8322ea65 100644
--- a/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_3.0_Helios/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -719,7 +719,7 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 				final double dropRateEffectBonus = killer.getStat().getValue(Stats.BONUS_DROP_RATE, 0);
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 				
 				// calculate if item will drop
diff --git a/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java b/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
index 4835bf1002..51b94e523e 100644
--- a/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
+++ b/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/bypasshandlers/NpcViewMod.java
@@ -505,7 +505,7 @@ public class NpcViewMod implements IBypassHandler
 				// bonus drop rate effect
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 			}
 			
diff --git a/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java b/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
index 28db8bde36..d6833be10e 100644
--- a/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
+++ b/L2J_Mobius_Classic_2.0_Saviors/dist/game/data/scripts/handlers/communityboard/DropSearchBoard.java
@@ -267,7 +267,7 @@ public class DropSearchBoard implements IParseBoardHandler
 						// bonus drop rate effect
 						if (dropRateEffectBonus > 0)
 						{
-							rateChance *= dropRateEffectBonus;
+							rateChance += rateChance * dropRateEffectBonus;
 						}
 					}
 					
diff --git a/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java b/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
index 64052a9c58..2c8322ea65 100644
--- a/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
+++ b/L2J_Mobius_Classic_2.0_Saviors/java/com/l2jmobius/gameserver/model/actor/templates/L2NpcTemplate.java
@@ -719,7 +719,7 @@ public final class L2NpcTemplate extends L2CharTemplate implements IIdentifiable
 				final double dropRateEffectBonus = killer.getStat().getValue(Stats.BONUS_DROP_RATE, 0);
 				if (dropRateEffectBonus > 0)
 				{
-					rateChance *= dropRateEffectBonus;
+					rateChance += rateChance * dropRateEffectBonus;
 				}
 				
 				// calculate if item will drop