diff --git a/build.sbt b/build.sbt
index 7a05e33f2..6f38ec8ea 100644
--- a/build.sbt
+++ b/build.sbt
@@ -25,7 +25,7 @@ lazy val compiler = crossProject.in(file(".")).
     organization := "io.kaitai",
     version := sys.env.getOrElse("KAITAI_STRUCT_VERSION", VERSION),
     licenses := Seq(("GPL-3.0", url("https://opensource.org/licenses/GPL-3.0"))),
-    scalaVersion := "2.12.4",
+    scalaVersion := "2.12.12",
 
     // Repo publish options
     publishTo := version { (v: String) =>
diff --git a/project/build.properties b/project/build.properties
index cabf73b45..dc8f331cc 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version = 1.2.7
+sbt.version = 1.4.3
diff --git a/project/plugins.sbt b/project/plugins.sbt
index 52104a18b..c1cb6dfe9 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -1,4 +1,4 @@
 logLevel := Level.Warn
 
 addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % "1.3.12")
-addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.28")
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.33")