diff --git a/worldedit-bukkit/adapters/adapter-1_21_4/build.gradle.kts b/worldedit-bukkit/adapters/adapter-1_21_4/build.gradle.kts
index 8e2d3c2036..f4bf8aa772 100644
--- a/worldedit-bukkit/adapters/adapter-1_21_4/build.gradle.kts
+++ b/worldedit-bukkit/adapters/adapter-1_21_4/build.gradle.kts
@@ -10,3 +10,9 @@ dependencies {
     the<PaperweightUserDependenciesExtension>().paperDevBundle("1.21.4-R0.1-20250609.101859-227")
     compileOnly(libs.paperLib)
 }
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(21))
+    }
+}
diff --git a/worldedit-bukkit/adapters/adapter-1_21_5/build.gradle.kts b/worldedit-bukkit/adapters/adapter-1_21_5/build.gradle.kts
index c3abf5b7bc..df9391e387 100644
--- a/worldedit-bukkit/adapters/adapter-1_21_5/build.gradle.kts
+++ b/worldedit-bukkit/adapters/adapter-1_21_5/build.gradle.kts
@@ -9,3 +9,9 @@ dependencies {
     the<PaperweightUserDependenciesExtension>().paperDevBundle("1.21.5-R0.1-20250618.110345-108")
     compileOnly(libs.paperLib)
 }
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(21))
+    }
+}
diff --git a/worldedit-bukkit/adapters/adapter-1_21_6/build.gradle.kts b/worldedit-bukkit/adapters/adapter-1_21_6/build.gradle.kts
index 4b156b4837..32dc5dd9bc 100644
--- a/worldedit-bukkit/adapters/adapter-1_21_6/build.gradle.kts
+++ b/worldedit-bukkit/adapters/adapter-1_21_6/build.gradle.kts
@@ -9,3 +9,9 @@ dependencies {
     the<PaperweightUserDependenciesExtension>().paperDevBundle("1.21.8-R0.1-20250829.204528-51")
     compileOnly(libs.paperLib)
 }
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(21))
+    }
+}
diff --git a/worldedit-bukkit/adapters/adapter-1_21_9/build.gradle.kts b/worldedit-bukkit/adapters/adapter-1_21_9/build.gradle.kts
index c7cc191e4a..891ea66ba8 100644
--- a/worldedit-bukkit/adapters/adapter-1_21_9/build.gradle.kts
+++ b/worldedit-bukkit/adapters/adapter-1_21_9/build.gradle.kts
@@ -9,3 +9,9 @@ dependencies {
     the<PaperweightUserDependenciesExtension>().paperDevBundle("1.21.10-R0.1-20251007.183616-3")
     compileOnly(libs.paperLib)
 }
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(21))
+    }
+}