diff --git a/src/sbt-test/ash/add-app-settings/build.sbt b/src/sbt-test/ash/add-app-settings/build.sbt
index 02421431c..400280e17 100644
--- a/src/sbt-test/ash/add-app-settings/build.sbt
+++ b/src/sbt-test/ash/add-app-settings/build.sbt
@@ -1,5 +1,7 @@
 enablePlugins(JavaAppPackaging, AshScriptPlugin)
 
+scalaVersion := "2.12.20"
+
 name := "simple-app"
 
 version := "0.1.0"
diff --git a/src/sbt-test/ash/command-line-settings/build.sbt b/src/sbt-test/ash/command-line-settings/build.sbt
index 234409f2c..175da3420 100644
--- a/src/sbt-test/ash/command-line-settings/build.sbt
+++ b/src/sbt-test/ash/command-line-settings/build.sbt
@@ -1,5 +1,7 @@
 enablePlugins(JavaAppPackaging, AshScriptPlugin)
 
+scalaVersion := "2.12.20"
+
 name := "command-line-app"
 
 version := "0.1.0-SNAPSHOT"
diff --git a/src/sbt-test/ash/memory-settings/build.sbt b/src/sbt-test/ash/memory-settings/build.sbt
index 48a3e128a..59d389df2 100644
--- a/src/sbt-test/ash/memory-settings/build.sbt
+++ b/src/sbt-test/ash/memory-settings/build.sbt
@@ -1,5 +1,7 @@
 enablePlugins(JavaAppPackaging, AshScriptPlugin)
 
+scalaVersion := "2.12.20"
+
 name := "simple-app"
 
 version := "0.1.0"
diff --git a/src/sbt-test/ash/override-templates/build.sbt b/src/sbt-test/ash/override-templates/build.sbt
index 51c1766cc..10b85158a 100644
--- a/src/sbt-test/ash/override-templates/build.sbt
+++ b/src/sbt-test/ash/override-templates/build.sbt
@@ -1,5 +1,7 @@
 import scala.io.Source
 
+scalaVersion := "2.12.20"
+
 enablePlugins(AshScriptPlugin)
 
 name := "override-templates"
diff --git a/src/sbt-test/ash/simple-app/build.sbt b/src/sbt-test/ash/simple-app/build.sbt
index 7343071d1..9d9c5526e 100644
--- a/src/sbt-test/ash/simple-app/build.sbt
+++ b/src/sbt-test/ash/simple-app/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(AshScriptPlugin)
 
 name := "simple-app"
diff --git a/src/sbt-test/ash/top-level-main/build.sbt b/src/sbt-test/ash/top-level-main/build.sbt
index 0633728fc..e306ed32d 100644
--- a/src/sbt-test/ash/top-level-main/build.sbt
+++ b/src/sbt-test/ash/top-level-main/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(AshScriptPlugin)
 
 name := "top-level-main"
diff --git a/src/sbt-test/bash/absolute-path-in-bash/build.sbt b/src/sbt-test/bash/absolute-path-in-bash/build.sbt
index b1453e8bb..0225e35cb 100644
--- a/src/sbt-test/bash/absolute-path-in-bash/build.sbt
+++ b/src/sbt-test/bash/absolute-path-in-bash/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "absolute-path-in-bash"
diff --git a/src/sbt-test/bash/java-home-var-expansion/build.sbt b/src/sbt-test/bash/java-home-var-expansion/build.sbt
index d106ba650..dfa1d4db2 100644
--- a/src/sbt-test/bash/java-home-var-expansion/build.sbt
+++ b/src/sbt-test/bash/java-home-var-expansion/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "java-home-override"
diff --git a/src/sbt-test/bash/memory-settings/build.sbt b/src/sbt-test/bash/memory-settings/build.sbt
index e64f3b293..3ceb242e0 100644
--- a/src/sbt-test/bash/memory-settings/build.sbt
+++ b/src/sbt-test/bash/memory-settings/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-app"
diff --git a/src/sbt-test/bash/multiple-apps/build.sbt b/src/sbt-test/bash/multiple-apps/build.sbt
index a1aabee2b..8f27558a7 100644
--- a/src/sbt-test/bash/multiple-apps/build.sbt
+++ b/src/sbt-test/bash/multiple-apps/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "test-project"
diff --git a/src/sbt-test/bash/override-templates/build.sbt b/src/sbt-test/bash/override-templates/build.sbt
index f14372d74..257d11f02 100644
--- a/src/sbt-test/bash/override-templates/build.sbt
+++ b/src/sbt-test/bash/override-templates/build.sbt
@@ -1,5 +1,7 @@
 import scala.io.Source
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "override-templates"
diff --git a/src/sbt-test/bash/simple-app/build.sbt b/src/sbt-test/bash/simple-app/build.sbt
index 43064cda4..acf534a17 100644
--- a/src/sbt-test/bash/simple-app/build.sbt
+++ b/src/sbt-test/bash/simple-app/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-app"
diff --git a/src/sbt-test/bash/top-level-main/build.sbt b/src/sbt-test/bash/top-level-main/build.sbt
index 9e823aeae..49630ce1f 100644
--- a/src/sbt-test/bash/top-level-main/build.sbt
+++ b/src/sbt-test/bash/top-level-main/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "top-level-main"
diff --git a/src/sbt-test/universal/absolute-path/build.sbt b/src/sbt-test/universal/absolute-path/build.sbt
index 988fe7f4c..1467c395d 100644
--- a/src/sbt-test/universal/absolute-path/build.sbt
+++ b/src/sbt-test/universal/absolute-path/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "absolute-path"
diff --git a/src/sbt-test/universal/application-ini-from-javaoptions/build.sbt b/src/sbt-test/universal/application-ini-from-javaoptions/build.sbt
index 00964eab6..1b65d4576 100644
--- a/src/sbt-test/universal/application-ini-from-javaoptions/build.sbt
+++ b/src/sbt-test/universal/application-ini-from-javaoptions/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaServerAppPackaging)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/clear-stage-dir/build.sbt b/src/sbt-test/universal/clear-stage-dir/build.sbt
index 3615d803a..30aca88ac 100644
--- a/src/sbt-test/universal/clear-stage-dir/build.sbt
+++ b/src/sbt-test/universal/clear-stage-dir/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(UniversalPlugin)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/dist/build.sbt b/src/sbt-test/universal/dist/build.sbt
index 3615d803a..30aca88ac 100644
--- a/src/sbt-test/universal/dist/build.sbt
+++ b/src/sbt-test/universal/dist/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(UniversalPlugin)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/multiproject-classifiers/build.sbt b/src/sbt-test/universal/multiproject-classifiers/build.sbt
index 6b99f2fd6..969991f40 100644
--- a/src/sbt-test/universal/multiproject-classifiers/build.sbt
+++ b/src/sbt-test/universal/multiproject-classifiers/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+ThisBuild / scalaVersion := "2.12.20"
+
 lazy val appVersion = "1.0"
 
 lazy val mySettings: Seq[Setting[_]] =
diff --git a/src/sbt-test/universal/publish/build.sbt b/src/sbt-test/universal/publish/build.sbt
index 0fca7bbd1..484c42014 100644
--- a/src/sbt-test/universal/publish/build.sbt
+++ b/src/sbt-test/universal/publish/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(UniversalDeployPlugin)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/staging-custom-main/build.sbt b/src/sbt-test/universal/staging-custom-main/build.sbt
index f9d5789f3..c7524fec6 100644
--- a/src/sbt-test/universal/staging-custom-main/build.sbt
+++ b/src/sbt-test/universal/staging-custom-main/build.sbt
@@ -6,6 +6,8 @@ name := "stage-custom-main"
 
 version := "0.1.0"
 
+scalaVersion := "2.12.20"
+
 Compile / mainClass := Some("Main")
 
 TaskKey[Unit]("unzip") := {
diff --git a/src/sbt-test/universal/staging/build.sbt b/src/sbt-test/universal/staging/build.sbt
index 3615d803a..30aca88ac 100644
--- a/src/sbt-test/universal/staging/build.sbt
+++ b/src/sbt-test/universal/staging/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(UniversalPlugin)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/test-executableScriptName/build.sbt b/src/sbt-test/universal/test-executableScriptName/build.sbt
index 300822822..4613bca67 100644
--- a/src/sbt-test/universal/test-executableScriptName/build.sbt
+++ b/src/sbt-test/universal/test-executableScriptName/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/test-mapping-helpers/build.sbt b/src/sbt-test/universal/test-mapping-helpers/build.sbt
index b21cf0613..08c0e6f40 100644
--- a/src/sbt-test/universal/test-mapping-helpers/build.sbt
+++ b/src/sbt-test/universal/test-mapping-helpers/build.sbt
@@ -2,6 +2,8 @@ import com.typesafe.sbt.packager.Compat._
 
 import com.typesafe.sbt.packager.MappingsHelper._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/test-native-zip/build.sbt b/src/sbt-test/universal/test-native-zip/build.sbt
index 95cbe0949..567f326ce 100644
--- a/src/sbt-test/universal/test-native-zip/build.sbt
+++ b/src/sbt-test/universal/test-native-zip/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/test-packageName/build.sbt b/src/sbt-test/universal/test-packageName/build.sbt
index a94707bcf..d5789cb51 100644
--- a/src/sbt-test/universal/test-packageName/build.sbt
+++ b/src/sbt-test/universal/test-packageName/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/test-zips-no-top-level-dir/build.sbt b/src/sbt-test/universal/test-zips-no-top-level-dir/build.sbt
index 45d9353e9..839579509 100644
--- a/src/sbt-test/universal/test-zips-no-top-level-dir/build.sbt
+++ b/src/sbt-test/universal/test-zips-no-top-level-dir/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/test-zips/build.sbt b/src/sbt-test/universal/test-zips/build.sbt
index de62e9544..0bb488202 100644
--- a/src/sbt-test/universal/test-zips/build.sbt
+++ b/src/sbt-test/universal/test-zips/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-test"
diff --git a/src/sbt-test/universal/validation/build.sbt b/src/sbt-test/universal/validation/build.sbt
index 3615d803a..30aca88ac 100644
--- a/src/sbt-test/universal/validation/build.sbt
+++ b/src/sbt-test/universal/validation/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(UniversalPlugin)
 
 name := "simple-test"
diff --git a/src/sbt-test/windows/absolute-path-in-bat/build.sbt b/src/sbt-test/windows/absolute-path-in-bat/build.sbt
index b70ed2804..8a6ac2b73 100644
--- a/src/sbt-test/windows/absolute-path-in-bat/build.sbt
+++ b/src/sbt-test/windows/absolute-path-in-bat/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "absolute-path-in-bat"
diff --git a/src/sbt-test/windows/app-home-var-expansion/build.sbt b/src/sbt-test/windows/app-home-var-expansion/build.sbt
index 2faa4e1c9..bb2293e35 100644
--- a/src/sbt-test/windows/app-home-var-expansion/build.sbt
+++ b/src/sbt-test/windows/app-home-var-expansion/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-app"
diff --git a/src/sbt-test/windows/custom-wix/build.sbt b/src/sbt-test/windows/custom-wix/build.sbt
index 3fb8fb142..1157efb0b 100644
--- a/src/sbt-test/windows/custom-wix/build.sbt
+++ b/src/sbt-test/windows/custom-wix/build.sbt
@@ -1,3 +1,5 @@
+scalaVersion := "2.12.20"
+
 enablePlugins(WindowsPlugin)
 
 name := "custom-wix"
diff --git a/src/sbt-test/windows/dynamic-app-env-name/build.sbt b/src/sbt-test/windows/dynamic-app-env-name/build.sbt
index 7f1bc09cd..917b88603 100644
--- a/src/sbt-test/windows/dynamic-app-env-name/build.sbt
+++ b/src/sbt-test/windows/dynamic-app-env-name/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "example-cli"
diff --git a/src/sbt-test/windows/java-app-archetype/build.sbt b/src/sbt-test/windows/java-app-archetype/build.sbt
index 0b60a8bdf..b93055ce4 100644
--- a/src/sbt-test/windows/java-app-archetype/build.sbt
+++ b/src/sbt-test/windows/java-app-archetype/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "windows-test"
diff --git a/src/sbt-test/windows/memory-settings/build.sbt b/src/sbt-test/windows/memory-settings/build.sbt
index 2dc61280a..a7a2a2b82 100644
--- a/src/sbt-test/windows/memory-settings/build.sbt
+++ b/src/sbt-test/windows/memory-settings/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "simple-app"
diff --git a/src/sbt-test/windows/multiple-apps/build.sbt b/src/sbt-test/windows/multiple-apps/build.sbt
index a1967fd8b..47e1d61a0 100644
--- a/src/sbt-test/windows/multiple-apps/build.sbt
+++ b/src/sbt-test/windows/multiple-apps/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "test-project"
diff --git a/src/sbt-test/windows/test-bat-template/build.sbt b/src/sbt-test/windows/test-bat-template/build.sbt
index 0e6948333..d249b91ad 100644
--- a/src/sbt-test/windows/test-bat-template/build.sbt
+++ b/src/sbt-test/windows/test-bat-template/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "windows-test"
diff --git a/src/sbt-test/windows/test-custom-main/build.sbt b/src/sbt-test/windows/test-custom-main/build.sbt
index 63c31d49f..69be5228c 100644
--- a/src/sbt-test/windows/test-custom-main/build.sbt
+++ b/src/sbt-test/windows/test-custom-main/build.sbt
@@ -1,5 +1,7 @@
 import com.typesafe.sbt.packager.Compat._
 
+scalaVersion := "2.12.20"
+
 enablePlugins(JavaAppPackaging)
 
 name := "test-custom-main"