diff --git a/headlessmc-launcher/src/main/java/me/earth/headlessmc/launcher/java/JavaService.java b/headlessmc-launcher/src/main/java/me/earth/headlessmc/launcher/java/JavaService.java
index 17358e79..43b11376 100644
--- a/headlessmc-launcher/src/main/java/me/earth/headlessmc/launcher/java/JavaService.java
+++ b/headlessmc-launcher/src/main/java/me/earth/headlessmc/launcher/java/JavaService.java
@@ -131,6 +131,11 @@ int parseSystemProperty(String versionIn) {
             if (dot != -1) {
                 version = version.substring(0, dot);
             }
+
+            int hyphen = version.indexOf("-"); // 21-internal
+            if (hyphen != -1) {
+                version = version.substring(0, hyphen);
+            }
         }
 
         return Integer.parseInt(version);
diff --git a/headlessmc-launcher/src/test/java/me/earth/headlessmc/launcher/java/JavaServiceTest.java b/headlessmc-launcher/src/test/java/me/earth/headlessmc/launcher/java/JavaServiceTest.java
index 0bf43e19..8c6260d1 100644
--- a/headlessmc-launcher/src/test/java/me/earth/headlessmc/launcher/java/JavaServiceTest.java
+++ b/headlessmc-launcher/src/test/java/me/earth/headlessmc/launcher/java/JavaServiceTest.java
@@ -40,6 +40,7 @@ public void testParseSystemProperty() {
         assertEquals(11, javaService.parseSystemProperty("11.0.2"));
         assertEquals(12, javaService.parseSystemProperty("12"));
         assertEquals(13, javaService.parseSystemProperty("13.0.1"));
+        assertEquals(21, javaService.parseSystemProperty("21-internal"));
     }
 
     @Test