diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index 1643412d8..dd9f5a177 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -3038,8 +3038,12 @@ object Classpaths {
     outputPath := {
       val p = platform.value
       val m = moduleName.value
+      val c = crossPaths.value
       val sv = scalaVersion.value
-      s"$p/scala-$sv/$m"
+      val sv1 =
+        if c then s"scala-$sv"
+        else "u"
+      s"$p/$sv1/$m"
     },
     ivyPaths := IvyPaths(
       baseDirectory.value.toString,
diff --git a/sbt-app/src/sbt-test/actions/doc/test b/sbt-app/src/sbt-test/actions/doc/test
index bed324217..0485cd45d 100644
--- a/sbt-app/src/sbt-test/actions/doc/test
+++ b/sbt-app/src/sbt-test/actions/doc/test
@@ -5,10 +5,10 @@
 # hybrid project, only scaladoc run
 > doc
 > packageBin
-$ exists target/out/jvm/scala-2.12.20/root/api/index.js
-$ exists target/out/jvm/scala-2.12.20/root/api/A$.html
-$ absent target/out/jvm/scala-2.12.20/root/api/scala
-$ absent target/out/jvm/scala-2.12.20/root/api/java
+$ exists target/out/jvm/u/root/api/index.js
+$ exists target/out/jvm/u/root/api/A$.html
+$ absent target/out/jvm/u/root/api/scala
+$ absent target/out/jvm/u/root/api/java
 
 > setDocExtension scala
 
@@ -19,12 +19,12 @@ $ copy-file changes/B.scala B.scala
 > clean ; compile ; doc
 
 # pure scala project, only scaladoc at top level
-$ exists target/out/jvm/scala-2.12.20/root/api/index.js
-$ exists target/out/jvm/scala-2.12.20/root/api/A$.html
-$ exists target/out/jvm/scala-2.12.20/root/api/B$.html
-$ absent target/out/jvm/scala-2.12.20/root/api/package-list
-$ absent target/out/jvm/scala-2.12.20/root/api/scala
-$ absent target/out/jvm/scala-2.12.20/root/api/java
+$ exists target/out/jvm/u/root/api/index.js
+$ exists target/out/jvm/u/root/api/A$.html
+$ exists target/out/jvm/u/root/api/B$.html
+$ absent target/out/jvm/u/root/api/package-list
+$ absent target/out/jvm/u/root/api/scala
+$ absent target/out/jvm/u/root/api/java
 
 > setDocExtension java
 
@@ -34,14 +34,14 @@ $ absent target/out/jvm/scala-2.12.20/root/api/java
 > doc
 
 # pure java project, only javadoc at top level
-$ exists target/out/jvm/scala-2.12.20/root/api/index.html
-$ exists target/out/jvm/scala-2.12.20/root/api/pkg/J.html
-$ absent target/out/jvm/scala-2.12.20/root/api/index.js
+$ exists target/out/jvm/u/root/api/index.html
+$ exists target/out/jvm/u/root/api/pkg/J.html
+$ absent target/out/jvm/u/root/api/index.js
 
 > setDocExtension scala
 > ++2.13.x
 > clean
-$ absent target/out/jvm/scala-2.12.20/root/api/A$.html
+$ absent target/out/jvm/u/root/api/A$.html
 > doc
-$ exists target/out/jvm/scala-2.13.12/root/api/A$.html
-$ exists target/out/jvm/scala-2.13.12/root/api/B$.html
+$ exists target/out/jvm/u/root/api/A$.html
+$ exists target/out/jvm/u/root/api/B$.html
diff --git a/sbt-app/src/sbt-test/package/lazy-name/test b/sbt-app/src/sbt-test/package/lazy-name/test
index f68ea1858..356e1d0a9 100644
--- a/sbt-app/src/sbt-test/package/lazy-name/test
+++ b/sbt-app/src/sbt-test/package/lazy-name/test
@@ -10,14 +10,14 @@
 
 > set version := "0.1.1"
 > package
-$ exists target/out/jvm/scala-3.3.1/lazy-package-name/lazy-package-name-0.1.1.jar
+$ exists target/out/jvm/u/lazy-package-name/lazy-package-name-0.1.1.jar
 > clean
 
 > set version := "0.1.2"
 > package
-$ exists target/out/jvm/scala-3.3.1/lazy-package-name/lazy-package-name-0.1.2.jar
+$ exists target/out/jvm/u/lazy-package-name/lazy-package-name-0.1.2.jar
 > clean
 
 > set version := "0.1.3"
 > package
-$ exists target/out/jvm/scala-3.3.1/lazy-package-name/lazy-package-name-0.1.3.jar
+$ exists target/out/jvm/u/lazy-package-name/lazy-package-name-0.1.3.jar
diff --git a/sbt-app/src/sbt-test/package/manifest/test b/sbt-app/src/sbt-test/package/manifest/test
index 1c162e9df..b4f26105b 100644
--- a/sbt-app/src/sbt-test/package/manifest/test
+++ b/sbt-app/src/sbt-test/package/manifest/test
@@ -1,4 +1,4 @@
 > package
-$ exists target/out/jvm/scala-2.12.18/jar-manifest-test/jar-manifest-test-0.2.jar
-$ exec java -jar ./target/out/jvm/scala-2.12.18/jar-manifest-test/jar-manifest-test-0.2.jar
+$ exists target/out/jvm/u/jar-manifest-test/jar-manifest-test-0.2.jar
+$ exec java -jar ./target/out/jvm/u/jar-manifest-test/jar-manifest-test-0.2.jar
 > run
diff --git a/sbt-app/src/sbt-test/package/resources/test b/sbt-app/src/sbt-test/package/resources/test
index 27ee7a65d..d31c184e9 100644
--- a/sbt-app/src/sbt-test/package/resources/test
+++ b/sbt-app/src/sbt-test/package/resources/test
@@ -10,7 +10,7 @@
 
 # This should fail because sbt should include the resource in the jar but it won't have the right
 # directory structure
--$ exec java -jar ./target/out/jvm/scala-3.3.1/main-resources-test/main-resources-test-0.1.jar
+-$ exec java -jar ./target/out/jvm/u/main-resources-test/main-resources-test-0.1.jar
 
 # Give the resource the right directory structure
 $ mkdir src/main/resources/jartest
@@ -27,4 +27,4 @@ $ delete src/main/resources/main_resource_test
 > package
 
 # This should succeed because sbt should include the resource in the jar with the right directory structure
-$ exec java -jar ./target/out/jvm/scala-3.3.1/main-resources-test/main-resources-test-0.1.jar
+$ exec java -jar ./target/out/jvm/u/main-resources-test/main-resources-test-0.1.jar
diff --git a/sbt-app/src/sbt-test/project1/lib/build.sbt b/sbt-app/src/sbt-test/project/lib/build.sbt
similarity index 71%
rename from sbt-app/src/sbt-test/project1/lib/build.sbt
rename to sbt-app/src/sbt-test/project/lib/build.sbt
index 440c8dbd8..cd7c60f18 100644
--- a/sbt-app/src/sbt-test/project1/lib/build.sbt
+++ b/sbt-app/src/sbt-test/project/lib/build.sbt
@@ -1,5 +1,3 @@
 crossPaths := false
-
 name := "definition-lib-test"
-  
-version := "1.0"
\ No newline at end of file
+version := "1.0"
diff --git a/sbt-app/src/sbt-test/project1/lib/changes/build2.sbt b/sbt-app/src/sbt-test/project/lib/changes/build2.sbt
similarity index 100%
rename from sbt-app/src/sbt-test/project1/lib/changes/build2.sbt
rename to sbt-app/src/sbt-test/project/lib/changes/build2.sbt
diff --git a/sbt-app/src/sbt-test/project/lib/src/main/scala/Test.scala b/sbt-app/src/sbt-test/project/lib/src/main/scala/Test.scala
new file mode 100644
index 000000000..b9c6b0a49
--- /dev/null
+++ b/sbt-app/src/sbt-test/project/lib/src/main/scala/Test.scala
@@ -0,0 +1,4 @@
+package injar
+
+object Test:
+  def foo: Option[String] = None
diff --git a/sbt-app/src/sbt-test/project1/lib/test b/sbt-app/src/sbt-test/project/lib/test
similarity index 80%
rename from sbt-app/src/sbt-test/project1/lib/test
rename to sbt-app/src/sbt-test/project/lib/test
index 2f46e6eae..6de060b02 100644
--- a/sbt-app/src/sbt-test/project1/lib/test
+++ b/sbt-app/src/sbt-test/project/lib/test
@@ -1,8 +1,8 @@
 # this step builds a test jar for use by the project definition
-> package
+> packageBin
 
 $ delete build.sbt
-$ copy-file target/definition-lib-test-1.0.jar project/lib/test.jar
+$ copy-file target/out/jvm/u/definition-lib-test/definition-lib-test-1.0.jar project/lib/test.jar
 $ copy-file changes/build2.sbt build.sbt
 
 # the copied project definition depends on the Test module in test.jar and will
diff --git a/sbt-app/src/sbt-test/project1/lib/src/main/scala/Test.scala b/sbt-app/src/sbt-test/project1/lib/src/main/scala/Test.scala
deleted file mode 100644
index bfa832aec..000000000
--- a/sbt-app/src/sbt-test/project1/lib/src/main/scala/Test.scala
+++ /dev/null
@@ -1,6 +0,0 @@
-package injar
-
-object Test
-{
-	def foo: Option[String] = None
-}
\ No newline at end of file