diff --git a/java/config/config.go b/java/config/config.go
index a795aad..333de32 100644
--- a/java/config/config.go
+++ b/java/config/config.go
@@ -90,12 +90,7 @@
 		if override := ctx.Config().Getenv("OVERRIDE_JLINK_VERSION_NUMBER"); override != "" {
 			return override
 		}
-		switch ctx.Config().Getenv("EXPERIMENTAL_USE_OPENJDK11_TOOLCHAIN") {
-		case "false":
-			return "9"
-		default:
-			return "11"
-		}
+		return "11"
 	})
 
 	pctx.SourcePathVariable("JavaToolchain", "${JavaHome}/bin")
diff --git a/ui/build/config.go b/ui/build/config.go
index 686ca3e..92aee4d 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -219,8 +219,8 @@
 		if override, ok := ret.environ.Get("OVERRIDE_ANDROID_JAVA_HOME"); ok {
 			return override
 		}
-		if toolchain9, ok := ret.environ.Get("EXPERIMENTAL_USE_OPENJDK11_TOOLCHAIN"); ok && toolchain9 == "false" {
-			return java9Home
+		if toolchain11, ok := ret.environ.Get("EXPERIMENTAL_USE_OPENJDK11_TOOLCHAIN"); ok && toolchain11 != "true" {
+			ctx.Fatalln("The environment variable EXPERIMENTAL_USE_OPENJDK11_TOOLCHAIN is no longer supported. An OpenJDK 11 toolchain is now the global default.")
 		}
 		return java11Home
 	}()