diff --git a/README.md b/README.md
index 054570d..269a3f6 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,7 @@
 # ⏳ Advanced PlayTime Plugin
 
 [![Build Status](https://github.com/imDMK/AdvancedPlayTime/actions/workflows/gradle.yml/badge.svg)](https://github.com/imDMK/AdvancedPlayTime/actions/workflows/gradle.yml)
-![JDK](https://img.shields.io/badge/JDK-25-blue.svg)
+![JDK](https://img.shields.io/badge/JDK-21%2B-blue.svg)
 ![Supported versions](https://img.shields.io/badge/Minecraft-1.21--26.2-green.svg)
 [![SpigotMC](https://img.shields.io/badge/SpigotMC-yellow.svg)](https://www.spigotmc.org/resources/%E2%8F%B0%EF%B8%8F-advancedplaytime-1-21-1-21-10.130458/)
 [![Modrinth](https://img.shields.io/badge/Modrinth-1bd96a.svg)](https://modrinth.com/plugin/advancedplaytime)
@@ -14,7 +14,7 @@
 ---
 
 ### 📦 Requirements
-- **Java 25** or newer on the server.
+- **Java 21** or newer on the server.
 - **Spigot / Paper 1.21 – 26.2**.
 
 ### ✨ Key Features
diff --git a/buildSrc/src/main/kotlin/Versions.kt b/buildSrc/src/main/kotlin/Versions.kt
index e445c89..d194382 100644
--- a/buildSrc/src/main/kotlin/Versions.kt
+++ b/buildSrc/src/main/kotlin/Versions.kt
@@ -1,7 +1,14 @@
 object Versions {
 
-    /** Java release the plugin is compiled for and requires at runtime. */
-    const val JAVA = 25
+    /** JDK the project is built with. */
+    const val JAVA_TOOLCHAIN = 25
+
+    /**
+     * Bytecode level of the shipped plugin, and therefore the oldest JVM a server may
+     * run it on. Kept at 21 because that is what Minecraft 1.21 itself requires — a
+     * higher target would lock the plugin out of the low end of the supported range.
+     */
+    const val JAVA_RELEASE = 21
 
     /** Spigot API the plugin is compiled against (newest supported server). */
     const val SPIGOT_API = "26.2-R0.1-SNAPSHOT"
diff --git a/buildSrc/src/main/kotlin/playtime-java.gradle.kts b/buildSrc/src/main/kotlin/playtime-java.gradle.kts
index 3336939..c79e5f5 100644
--- a/buildSrc/src/main/kotlin/playtime-java.gradle.kts
+++ b/buildSrc/src/main/kotlin/playtime-java.gradle.kts
@@ -6,11 +6,11 @@ group = "com.github.imdmk"
 version = "3.0.2"
 
 java {
-    toolchain.languageVersion.set(JavaLanguageVersion.of(Versions.JAVA))
+    toolchain.languageVersion.set(JavaLanguageVersion.of(Versions.JAVA_TOOLCHAIN))
 }
 
 tasks.withType<JavaCompile>().configureEach {
     options.compilerArgs = listOf("-Xlint:deprecation", "-parameters")
     options.encoding = "UTF-8"
-    options.release.set(Versions.JAVA)
+    options.release.set(Versions.JAVA_RELEASE)
 }
diff --git a/playtime-plugin/build.gradle.kts b/playtime-plugin/build.gradle.kts
index 4eb2380..6920070 100644
--- a/playtime-plugin/build.gradle.kts
+++ b/playtime-plugin/build.gradle.kts
@@ -30,7 +30,7 @@ playTimeShadow {
     }
 
     shadowJar {
-        archiveFileName.set("AdvancedPlayTime v${project.version} (MC 1.21-26.2, Java ${Versions.JAVA}).jar")
+        archiveFileName.set("AdvancedPlayTime v${project.version} (MC 1.21-26.2, Java ${Versions.JAVA_RELEASE}).jar")
 
         mergeServiceFiles()