diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze-update/build.sbt b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze-update/build.sbt
new file mode 100644
index 000000000..ed6887bc4
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze-update/build.sbt
@@ -0,0 +1,4 @@
+lazy val a = project.settings(
+  scalaVersion := "2.13.4",
+  libraryDependencies += "org.scala-lang.modules" %% "scala-parallel-collections" % "1.0.4", // depends on library 2.13.6
+)
diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze-update/test b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze-update/test
new file mode 100644
index 000000000..7f263ab0b
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze-update/test
@@ -0,0 +1,3 @@
+-> a/scalaInstance
+> set a/scalaVersion := "2.13.6"
+> a/scalaInstance
diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/a/A.scala b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/a/A.scala
new file mode 100644
index 000000000..d1522c579
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/a/A.scala
@@ -0,0 +1,20 @@
+import scala.language.reflectiveCalls
+
+object A extends App {
+  println(scala.util.Properties.versionString)
+}
+
+object AMacro {
+  import scala.language.experimental.macros
+  import scala.reflect.macros.blackbox.Context
+
+  def m(x: Int): Int = macro impl
+
+  def impl(c: Context)(x: c.Expr[Int]): c.Expr[Int] = {
+    import c.universe._
+    // added in 2.13.4
+    val ec = (scala.concurrent.ExecutionContext: {def opportunistic: scala.concurrent.ExecutionContextExecutor}).opportunistic
+    println(ec)
+    c.Expr(q"2 + $x")
+  }
+}
diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/a3/A.scala b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/a3/A.scala
new file mode 100644
index 000000000..e6f35a100
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/a3/A.scala
@@ -0,0 +1,17 @@
+import scala.quoted.* // imports Quotes, Expr
+
+package scala.collection {
+  object Exp:
+    // added in 2.13.10, not available in 2.13.8
+    def m(i: Int) = IterableOnce.checkArraySizeWithinVMLimit(i)
+}
+
+object Mac:
+  inline def inspect(inline x: Any): Any = ${ inspectCode('x) }
+
+  def inspectCode(x: Expr[Any])(using Quotes): Expr[Any] =
+    scala.collection.Exp.m(42)
+    println(x.show)
+    x
+
+@main def huhu = println(scala.util.Properties.versionString)
diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/b/B.scala b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/b/B.scala
new file mode 100644
index 000000000..e24101062
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/b/B.scala
@@ -0,0 +1,7 @@
+import java.nio.file.{Paths, Files}
+import java.nio.charset.StandardCharsets
+
+object B extends App {
+  println(AMacro.m(33))
+  Files.write(Paths.get(s"s${scala.util.Properties.versionNumberString}.txt"), "nix".getBytes)
+}
diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/b3/B.scala b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/b3/B.scala
new file mode 100644
index 000000000..a011c5c95
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/b3/B.scala
@@ -0,0 +1,6 @@
+import java.nio.file.{Paths, Files}
+import java.nio.charset.StandardCharsets
+
+@main def hubu =
+  Mac.inspect(println("hai"))
+  Files.write(Paths.get(s"s${scala.util.Properties.versionNumberString}.txt"), "nix".getBytes)
diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/build.sbt b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/build.sbt
new file mode 100644
index 000000000..901101cea
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/build.sbt
@@ -0,0 +1,46 @@
+import sbt.librarymanagement.InclExclRule
+
+lazy val a = project.settings(
+  scalaVersion := "2.13.6",
+  libraryDependencies += "org.scala-lang" % "scala-reflect" % scalaVersion.value,
+  TaskKey[Unit]("checkLibs") := checkLibs("2.13.6", (Compile/dependencyClasspath).value, ".*scala-(library|reflect).*"),
+)
+
+lazy val b = project.dependsOn(a).settings(
+  scalaVersion := "2.13.8",
+  TaskKey[Unit]("checkLibs") := checkLibs("2.13.8", (Compile/dependencyClasspath).value, ".*scala-(library|reflect).*"),
+)
+
+lazy val a3 = project.settings(
+  scalaVersion := "3.2.2", // 2.13.10 library
+)
+
+lazy val b3 = project.dependsOn(a3).settings(
+  scalaVersion := "3.2.0", // 2.13.8 library
+  TaskKey[Unit]("checkScala") := {
+    val i = scalaInstance.value
+    i.libraryJars.filter(_.toString.contains("scala-library")).toList match {
+      case List(l) => assert(l.toString.contains("2.13.10"), i.toString)
+    }
+    assert(i.compilerJars.filter(_.toString.contains("scala-library")).isEmpty, i.toString)
+    assert(i.otherJars.filter(_.toString.contains("scala-library")).isEmpty, i.toString)
+  },
+)
+
+lazy val ak = project.settings(
+  scalaVersion := "2.13.12",
+  csrSameVersions += Set[InclExclRule]("com.typesafe.akka" % "akka-*"),
+  libraryDependencies ++= Seq(
+    "com.typesafe.akka" %% "akka-remote" % "2.6.5",
+    "com.typesafe.akka" %% "akka-actor" % "2.6.2",
+  ),
+  TaskKey[Unit]("checkLibs") := checkLibs("2.6.5", (Compile/dependencyClasspath).value, ".*akka-.*"),
+)
+
+def checkLibs(v: String, cp: Classpath, filter: String): Unit = {
+  for (p <- cp)
+    if (p.toString.matches(filter)) {
+      println(s"$p -- $v")
+      assert(p.toString.contains(v), p)
+    }
+}
diff --git a/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/test b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/test
new file mode 100644
index 000000000..7df93ab6c
--- /dev/null
+++ b/sbt-app/src/sbt-test/dependency-management/stdlib-unfreeze/test
@@ -0,0 +1,20 @@
+> a/checkLibs
+> b/checkLibs
+
+> b/run
+$ exists s2.13.8.txt
+$ delete s2.13.8.txt
+
+# don't crash when expanding the macro
+> b3/run
+$ exists s2.13.10.txt
+$ delete s2.13.10.txt
+
+> b3/checkScala
+
+# without the default `csrSameVersions`, scala-reflect in b stays at 2.13.6
+> set b/csrSameVersions := Nil
+> b/update
+-> b/checkLibs
+
+> ak/checkLibs