diff --git a/core/define/src/mill/define/Task.scala b/core/define/src/mill/define/Task.scala
index 55374fe4782f..f16a5b2ec590 100644
--- a/core/define/src/mill/define/Task.scala
+++ b/core/define/src/mill/define/Task.scala
@@ -148,34 +148,30 @@ object Task {
    * signature for you source files/folders and decides whether or not downstream
    * [[Task.Computed]]s need to be invalidated and re-computed.
    */
-  inline def Sources(inline values: Result[os.Path]*)(implicit
+  inline def Sources(inline values: (os.SubPath | os.FilePath)*)(implicit
       inline ctx: mill.define.ModuleCtx
   ): Simple[Seq[PathRef]] = ${
-    Macros.sourcesImpl('{ Result.sequence(values.map(_.map(PathRef(_)))) })('ctx)
+    Macros.sourcesImpl('{ values.map(p => PathRef(mapToPath(p))) })('ctx)
   }
 
-  inline def Sources(inline values: os.SubPath*)(implicit
-      inline ctx: mill.define.ModuleCtx,
-      dummy: Boolean = true
-  ): Simple[Seq[PathRef]] = ${
-    Macros.sourcesImpl(
-      '{ values.map(sub => PathRef(ctx.millSourcePath / os.up / os.PathChunk.SubPathChunk(sub))) }
-    )('ctx)
+  inline private def mapToPath(value: os.SubPath | os.FilePath)(implicit
+      inline ctx: mill.define.ModuleCtx
+  ): os.Path = value match {
+    // TODO: support "."
+    case str: String => ctx.millSourcePath / os.up / os.PathChunk.segmentsFromString(str)
+    case sub: os.SubPath => ctx.millSourcePath / os.up / os.PathChunk.SubPathChunk(sub)
+    case rel: os.RelPath => ctx.millSourcePath / os.up / os.PathChunk.RelPathChunk(rel)
+    case p: os.Path => p
   }
 
   /**
    * Similar to [[Sources]], but only for a single source file or folder. Defined
    * using `Task.Source`.
    */
-  inline def Source(inline value: Result[os.Path])(implicit
-      inline ctx: mill.define.ModuleCtx
-  ): Simple[PathRef] =
-    ${ Macros.sourceImpl('{ value.map(PathRef(_)) })('ctx) }
-
-  inline def Source(inline value: os.SubPath)(implicit
+  inline def Source(inline value: os.SubPath | os.FilePath)(implicit
       inline ctx: mill.define.ModuleCtx
   ): Simple[PathRef] =
-    ${ Macros.sourceImpl('{ PathRef(ctx.millSourcePath / os.up / value) })('ctx) }
+    ${ Macros.sourceImpl('{ PathRef(mapToPath(value)) })('ctx) }
 
   /**
    * [[Input]]s, normally defined using `Task.Input`, are [[Task.Named]]s that
diff --git a/core/exec/test/src/mill/exec/ExecutionTests.scala b/core/exec/test/src/mill/exec/ExecutionTests.scala
index 452fa8df7784..e0b8ce5bd424 100644
--- a/core/exec/test/src/mill/exec/ExecutionTests.scala
+++ b/core/exec/test/src/mill/exec/ExecutionTests.scala
@@ -32,6 +32,19 @@ object ExecutionTests extends TestSuite {
     def task = Task[Int] { anon() }
     lazy val millDiscover = Discover[this.type]
   }
+
+  object sourceBuild extends TestRootModule {
+    def source = Task.Source { "hello/world.txt" }
+    def task = Task { os.read(source().path) + " !" }
+    lazy val millDiscover = Discover[this.type]
+  }
+
+  object sourcesBuild extends TestRootModule {
+    def source = Task.Sources("hello/world.txt", "hello/world2.txt")
+    def task = Task { source().map(pr => os.read(pr.path)).mkString + "!" }
+    lazy val millDiscover = Discover[this.type]
+  }
+
   class Checker[T <: mill.testkit.TestRootModule](module: T)
       extends exec.Checker(module)
 
@@ -45,12 +58,7 @@ object ExecutionTests extends TestSuite {
     }
 
     test("source") {
-      object build extends TestRootModule {
-        def source = Task.Source { "hello/world.txt" }
-        def task = Task { os.read(source().path) + " !" }
-        lazy val millDiscover = Discover[this.type]
-      }
-
+      val build = sourceBuild
       val checker = new Checker(build)
 
       os.write(build.moduleDir / "hello/world.txt", "i am cow", createFolders = true)
@@ -61,7 +69,13 @@ object ExecutionTests extends TestSuite {
         extraEvaled = -1,
         secondRunNoOp = false
       )
-      checker(build.task, "i am cow !", Seq(build.source), extraEvaled = -1, secondRunNoOp = false)
+      checker(
+        build.task,
+        "i am cow !",
+        Seq(build.source),
+        extraEvaled = -1,
+        secondRunNoOp = false
+      )
       os.write.over(build.moduleDir / "hello/world.txt", "hear me moo")
 
       checker(
@@ -80,12 +94,7 @@ object ExecutionTests extends TestSuite {
       )
     }
     test("sources") {
-      object build extends TestRootModule {
-        def source = Task.Sources("hello/world.txt", "hello/world2.txt")
-        def task = Task { source().map(pr => os.read(pr.path)).mkString + "!" }
-        lazy val millDiscover = Discover[this.type]
-      }
-
+      val build = sourcesBuild
       val checker = new Checker(build)
 
       os.write(build.moduleDir / "hello/world.txt", "i am cow ", createFolders = true)
@@ -298,10 +307,10 @@ object ExecutionTests extends TestSuite {
 
       UnitTester(build, null).scoped { tester =>
         assert(y == 0)
-        val Right(_) = tester.apply(build.task)
+        val Right(_) = tester.apply(build.task): @unchecked
         assert(y == 10)
         x = 0
-        val Left(_) = tester.apply(build.task)
+        val Left(_) = tester.apply(build.task): @unchecked
         assert(y == 10)
       }
     }
@@ -315,12 +324,13 @@ object ExecutionTests extends TestSuite {
         lazy val millDiscover = Discover[this.type]
       }
       UnitTester(build, null).scoped { tester =>
-        val Right(UnitTester.Result(Seq(1, 10, 100), _)) = tester.apply(build.task4)
+        val Right(UnitTester.Result(Seq(1, 10, 100), _)) = tester.apply(build.task4): @unchecked
       }
     }
     test("traverse") {
       UnitTester(traverseBuild, null).scoped { tester =>
-        val Right(UnitTester.Result(Seq(1, 10, 100), _)) = tester.apply(traverseBuild.task4)
+        val Right(UnitTester.Result(Seq(1, 10, 100), _)) =
+          tester.apply(traverseBuild.task4): @unchecked
       }
     }
 
@@ -332,7 +342,7 @@ object ExecutionTests extends TestSuite {
         lazy val millDiscover = Discover[this.type]
       }
       UnitTester(build, null).scoped { tester =>
-        val Right(UnitTester.Result((1, 10), _)) = tester.apply(build.task4)
+        val Right(UnitTester.Result((1, 10), _)) = tester.apply(build.task4): @unchecked
       }
     }
 
@@ -344,7 +354,7 @@ object ExecutionTests extends TestSuite {
         lazy val millDiscover = Discover[this.type]
       }
       UnitTester(build, null).scoped { tester =>
-        val Right(UnitTester.Result(11, _)) = tester.apply(build.task2)
+        val Right(UnitTester.Result(11, _)) = tester.apply(build.task2): @unchecked
       }
     }
 
@@ -421,13 +431,17 @@ object ExecutionTests extends TestSuite {
 
     test("backticked") {
       UnitTester(bactickIdentifiers, null).scoped { tester =>
-        val Right(UnitTester.Result(1, _)) = tester.apply(bactickIdentifiers.`up-target`)
-        val Right(UnitTester.Result(3, _)) = tester.apply(bactickIdentifiers.`a-down-target`)
-        val Right(UnitTester.Result(3, _)) = tester.apply(bactickIdentifiers.`invisible&`)
+        val Right(UnitTester.Result(1, _)) =
+          tester.apply(bactickIdentifiers.`up-target`): @unchecked
+        val Right(UnitTester.Result(3, _)) =
+          tester.apply(bactickIdentifiers.`a-down-target`): @unchecked
+        val Right(UnitTester.Result(3, _)) =
+          tester.apply(bactickIdentifiers.`invisible&`): @unchecked
         val Right(UnitTester.Result(4, _)) =
-          tester.apply(bactickIdentifiers.`nested-module`.`nested-target`)
+          tester.apply(bactickIdentifiers.`nested-module`.`nested-target`): @unchecked
       }
     }
+
     test("anonTaskFailure") {
       UnitTester(anonTaskFailure, null).scoped { tester =>
         val res = tester.evaluator.execute(Seq(anonTaskFailure.task))
diff --git a/example/fundamentals/tasks/2-primary-tasks/build.mill b/example/fundamentals/tasks/2-primary-tasks/build.mill
index 24e0b13b08e6..39a486c3bc32 100644
--- a/example/fundamentals/tasks/2-primary-tasks/build.mill
+++ b/example/fundamentals/tasks/2-primary-tasks/build.mill
@@ -12,8 +12,10 @@ import mill.{Module, T, _}
 def sources = Task.Source { "src" }
 def resources = Task.Source { "resources" }
 
-// ``Source``s are defined using `Task.Source{...}` taking one `os.Path`, or `Task.Sources{...}`,
-// taking multiple ``os.Path``s as arguments. A ``Source``'s:
+// ``Source``s are defined using `Task.Source{...}` taking one path, or `Task.Sources{...}`,
+// taking multiple paths as arguments. Both accept `os.Path`, `os.SubPath`, `os.RelPath`
+// or a `String` containing a sub-path. All relative paths will be resolve against the `moduleDir`
+// of the enclosing module. A ``Source``'s:
 // its build signature/`hashCode` depends not just on the path
 // it refers to (e.g. `foo/bar/baz`) but also the MD5 hash of the file contents or
 // folder tree at that path.
diff --git a/example/thirdparty/arrow/build.mill b/example/thirdparty/arrow/build.mill
index 95d83864495b..7df92b276081 100644
--- a/example/thirdparty/arrow/build.mill
+++ b/example/thirdparty/arrow/build.mill
@@ -143,7 +143,7 @@ object `package` extends Module {
             sources ++= Seq(nonJvmSourcesPath)
           }
         }
-        sources.map(mill.api.Result.Success(_))
+        sources
       }*)
 
       override def kotlincOptions =
@@ -163,8 +163,7 @@ object `package` extends Module {
         override def sources: T[Seq[PathRef]] = Task.Sources(
           Seq("common", outer.platformCrossSuffix)
             .map(platform => outer.moduleDir / "src" / s"${platform}Test" / "kotlin")
-            .filter(p => os.exists(p))
-            .map(mill.api.Result.Success(_))*
+            .filter(p => os.exists(p))*
         )
       }
     }
diff --git a/libs/scalalib/test/src/mill/javalib/revapi/RevapiModuleTests.scala b/libs/scalalib/test/src/mill/javalib/revapi/RevapiModuleTests.scala
index 0a9b7e2b102a..9534abccd447 100644
--- a/libs/scalalib/test/src/mill/javalib/revapi/RevapiModuleTests.scala
+++ b/libs/scalalib/test/src/mill/javalib/revapi/RevapiModuleTests.scala
@@ -73,7 +73,7 @@ object RevapiModuleTests extends TestSuite {
     object module2 extends module with RevapiModule {
       override def revapiConfigFiles: T[Seq[PathRef]] =
         Task.Sources(
-          os.list(conf).iterator.filter(_.ext == "json").toSeq.map(mill.api.Result.Success(_))*
+          os.list(conf).iterator.filter(_.ext == "json").toSeq*
         )
       override def revapiClasspath: T[Seq[PathRef]] = Task {
         super.revapiClasspath() ++ Seq(PathRef(conf))
@@ -113,7 +113,7 @@ object RevapiModuleTests extends TestSuite {
       }
       override def revapiConfigFiles: T[Seq[PathRef]] =
         Task.Sources(
-          os.list(conf).iterator.filter(_.ext == "json").toSeq.map(mill.api.Result.Success(_))*
+          os.list(conf).iterator.filter(_.ext == "json").toSeq*
         )
       override def revapiClasspath: T[Seq[PathRef]] = Task {
         super.revapiClasspath() ++ Seq(PathRef(conf))
diff --git a/runner/meta/src/mill/meta/MillBuildRootModule.scala b/runner/meta/src/mill/meta/MillBuildRootModule.scala
index 0f5c887a394f..09236cb3c487 100644
--- a/runner/meta/src/mill/meta/MillBuildRootModule.scala
+++ b/runner/meta/src/mill/meta/MillBuildRootModule.scala
@@ -48,7 +48,7 @@ trait MillBuildRootModule()(implicit
    * @see [[generatedSources]]
    */
   def scriptSources: T[Seq[PathRef]] = Task.Sources(
-    scriptSourcesPaths.map(Result.Success(_))* // Ensure ordering is deterministic
+    scriptSourcesPaths* // Ensure ordering is deterministic
   )
 
   def parseBuildFiles: T[FileImportGraph] = Task {