diff --git a/src/main/java/ch/njol/skript/effects/EffWorldBorderExpand.java b/src/main/java/ch/njol/skript/effects/EffWorldBorderExpand.java
index 045a6e51447..6bc58e756bf 100644
--- a/src/main/java/ch/njol/skript/effects/EffWorldBorderExpand.java
+++ b/src/main/java/ch/njol/skript/effects/EffWorldBorderExpand.java
@@ -14,10 +14,13 @@
 import ch.njol.skript.util.Timespan.TimePeriod;
 import ch.njol.util.Kleenean;
 import ch.njol.util.Math2;
+import org.bukkit.Bukkit;
 import org.bukkit.WorldBorder;
 import org.bukkit.event.Event;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Objects;
+
 @Name("Expand/Shrink World Border")
 @Description({
 	"Expand or shrink the size of a world border.",
@@ -80,14 +83,23 @@ protected void execute(Event event) {
 		if (to) {
 			input = Math2.fit(1, input, MAX_WORLDBORDER_SIZE);
 			for (WorldBorder worldBorder : worldBorders)
-				worldBorder.setSize(input, speed);
+				if (Objects.equals(Bukkit.getBukkitVersion().split("-")[0], "1.21.11")) {
+					worldBorder.changeSize(input, speed);
+				} else {
+					worldBorder.setSize(input, speed);
+
+				}
 		} else {
 			if (shrink)
 				input = -input;
 			for (WorldBorder worldBorder : worldBorders) {
 				double size = worldBorder.getSize();
 				size = Math2.fit(1, size + input, MAX_WORLDBORDER_SIZE);
-				worldBorder.setSize(size, speed);
+				if (Objects.equals(Bukkit.getBukkitVersion().split("-")[0], "1.21.11")) {
+					worldBorder.changeSize(size, speed);
+				} else {
+					worldBorder.setSize(size, speed);
+				}
 			}
 		}
 	}
diff --git a/src/main/java/ch/njol/skript/expressions/ExprWorldBorder.java b/src/main/java/ch/njol/skript/expressions/ExprWorldBorder.java
index 90ee78c974e..d9772b5da94 100644
--- a/src/main/java/ch/njol/skript/expressions/ExprWorldBorder.java
+++ b/src/main/java/ch/njol/skript/expressions/ExprWorldBorder.java
@@ -7,12 +7,15 @@
 import ch.njol.skript.doc.Since;
 import ch.njol.skript.expressions.base.SimplePropertyExpression;
 import ch.njol.util.coll.CollectionUtils;
+import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.WorldBorder;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Event;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Objects;
+
 @Name("World Border")
 @Description({
 	"Get the border of a world or a player.",
@@ -64,7 +67,12 @@ public void change(Event event, Object @Nullable [] delta, ChangeMode mode) {
 				worldBorder.setDamageAmount(to.getDamageAmount());
 				worldBorder.setDamageBuffer(to.getDamageBuffer());
 				worldBorder.setWarningDistance(to.getWarningDistance());
-				worldBorder.setWarningTime(to.getWarningTime());
+				if (Objects.equals(Bukkit.getBukkitVersion().split("-")[0], "1.21.11")) {
+					worldBorder.setWarningTimeTicks(to.getWarningTimeTicks());
+				} else {
+					worldBorder.setWarningTime(to.getWarningTime());
+
+				}
 			} else if (object instanceof Player player) {
 				player.setWorldBorder(to);
 			}
diff --git a/src/main/java/ch/njol/skript/expressions/ExprWorldBorderWarningTime.java b/src/main/java/ch/njol/skript/expressions/ExprWorldBorderWarningTime.java
index bac607fbf9e..d42529d02b0 100644
--- a/src/main/java/ch/njol/skript/expressions/ExprWorldBorderWarningTime.java
+++ b/src/main/java/ch/njol/skript/expressions/ExprWorldBorderWarningTime.java
@@ -11,10 +11,13 @@
 import ch.njol.skript.util.Timespan.TimePeriod;
 import ch.njol.util.Math2;
 import ch.njol.util.coll.CollectionUtils;
+import org.bukkit.Bukkit;
 import org.bukkit.WorldBorder;
 import org.bukkit.event.Event;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.Objects;
+
 @Name("Warning Time of World Border")
 @Description("The warning time of a world border. If the border is shrinking, the player's screen will be tinted red once the border will catch the player within this time period.")
 @Example("set world border warning time of {_worldborder} to 1 second")
@@ -27,7 +30,7 @@ public class ExprWorldBorderWarningTime extends SimplePropertyExpression<WorldBo
 
 	@Override
 	public @Nullable Timespan convert(WorldBorder worldBorder) {
-		return new Timespan(TimePeriod.SECOND, worldBorder.getWarningTime());
+		return new Timespan(TimePeriod.SECOND, worldBorder.getWarningTimeTicks());
 	}
 
 	@Override
@@ -42,10 +45,13 @@ public class ExprWorldBorderWarningTime extends SimplePropertyExpression<WorldBo
 	public void change(Event event, Object @Nullable [] delta, ChangeMode mode) {
 		long input = delta == null ? 15 : (((Timespan) delta[0]).getAs(TimePeriod.SECOND));
 		for (WorldBorder worldBorder : getExpr().getArray(event)) {
+			long warnTime = Objects.equals(Bukkit.getBukkitVersion().split("-")[0], "1.21.11")
+				? worldBorder.getWarningTimeTicks()
+				: worldBorder.getWarningTime();
 			long warningTime = switch (mode) {
 				case SET, RESET -> input;
-				case ADD -> Math2.addClamped(worldBorder.getWarningTime(), input);
-				case REMOVE -> Math2.addClamped(worldBorder.getWarningTime(), -input);
+				case ADD -> Math2.addClamped(warnTime, input);
+				case REMOVE -> Math2.addClamped(warnTime, -input);
 				default -> throw new IllegalStateException();
 			};
 			setWarningTime(worldBorder, warningTime);
@@ -57,7 +63,13 @@ private static void setWarningTime(WorldBorder worldBorder, long inputTime) {
 		long time = Math2.multiplyClamped(inputTime, 20);
 		// fit and convert back to seconds
 		int warningTime = ((int) Math2.fit(0, time, Integer.MAX_VALUE)) / 20;
-		worldBorder.setWarningTime(warningTime);
+		if (Objects.equals(Bukkit.getBukkitVersion().split("-")[0], "1.21.11")) {
+			worldBorder.setWarningTimeTicks(warningTime);
+		} else {
+			worldBorder.setWarningTime(warningTime);
+
+		}
+
 	}
 
 	@Override