diff --git a/project/AkkaBuild.scala b/project/AkkaBuild.scala
index 0dc3449ff3..17ce0fe237 100644
--- a/project/AkkaBuild.scala
+++ b/project/AkkaBuild.scala
@@ -786,6 +786,11 @@ object AkkaBuild extends Build {
 
   val validatePullRequest = TaskKey[Unit]("validate-pull-request", "Additional tasks for pull request validation")
 
+  def githubUrl(v: String): String = {
+    val branch = if (v.endsWith("SNAPSHOT")) "master" else "v" + v
+    "http://github.com/akka/akka/tree/" + branch
+  }
+
   // preprocessing settings for sphinx
   lazy val sphinxPreprocessing = inConfig(Sphinx)(Seq(
     target in preprocess <<= baseDirectory / "rst_preprocessed",
@@ -793,7 +798,6 @@ object AkkaBuild extends Build {
     // customization of sphinx @<key>@ replacements, add to all sphinx-using projects
     // add additional replacements here
     preprocessVars <<= (scalaVersion, version) { (s, v) =>
-      val isSnapshot = v.endsWith("SNAPSHOT")
       val BinVer = """(\d+\.\d+)\.\d+""".r
       Map(
         "version" -> v,
@@ -811,7 +815,7 @@ object AkkaBuild extends Build {
             case _          => s
           }),
         "sigarVersion" -> Dependencies.Compile.sigar.revision,
-        "github" -> "http://github.com/akka/akka/tree/%s".format((if (isSnapshot) "master" else "v" + v))
+        "github" -> githubUrl(v)
       )
     },
     preprocess <<= (sourceDirectory, target in preprocess, cacheDirectory, preprocessExts, preprocessVars, streams) map {
@@ -888,7 +892,11 @@ object AkkaBuild extends Build {
   lazy val scaladocDiagramsEnabled = System.getProperty("akka.scaladoc.diagrams", "false").toBoolean
   lazy val scaladocAutoAPI = System.getProperty("akka.scaladoc.autoapi", "true").toBoolean
 
-  lazy val scaladocOptions = List("-implicits") ::: (if (scaladocDiagramsEnabled) List("-diagrams") else Nil)
+  def scaladocOptions(ver: String, base: File): List[String] = {
+    val urlString = githubUrl(ver) + "/€{FILE_PATH}.scala"
+    val opts = List("-implicits", "-doc-source-url", urlString, "-sourcepath", base.getAbsolutePath)
+    if (scaladocDiagramsEnabled) "-diagrams"::opts else opts
+  }
 
   lazy val scaladocSettings: Seq[sbt.Setting[_]] = {
     scaladocSettingsNoVerificationOfDiagrams ++
@@ -896,18 +904,19 @@ object AkkaBuild extends Build {
   }
   
   // for projects with few (one) classes there might not be any diagrams
-  lazy val scaladocSettingsNoVerificationOfDiagrams: Seq[sbt.Setting[_]]= {
-    Seq(
-      scalacOptions in (Compile, doc) ++= scaladocOptions,
+  lazy val scaladocSettingsNoVerificationOfDiagrams: Seq[sbt.Setting[_]] = {
+    inTask(doc)(Seq(
+      scalacOptions in Compile <++= (version, baseDirectory in akka) map scaladocOptions,
       autoAPIMappings := scaladocAutoAPI
-    )
+    ))
   }
   
   lazy val unidocScaladocSettings: Seq[sbt.Setting[_]]= {
-    Seq(scalacOptions in doc ++= scaladocOptions) ++
-      (if (scaladocDiagramsEnabled)
-        Seq(sunidoc ~= scaladocVerifier)
-      else Seq.empty)
+    inTask(doc)(Seq(
+      scalacOptions <++= (version, baseDirectory in akka) map scaladocOptions,
+      autoAPIMappings := scaladocAutoAPI
+    )) ++
+    (if (scaladocDiagramsEnabled) Seq(sunidoc ~= scaladocVerifier) else Seq.empty)
   }
 
   def scaladocVerifier(file: File): File= {
diff --git a/project/Unidoc.scala b/project/Unidoc.scala
index 0ff23d1585..b1bc8ef2eb 100644
--- a/project/Unidoc.scala
+++ b/project/Unidoc.scala
@@ -68,10 +68,11 @@ object Unidoc {
   }
 
   def sunidocTask: Initialize[Task[File]] = {
-    (compilers, cacheDirectory, unidocSources, unidocClasspath, unidocDirectory, scalacOptions in doc, streams) map {
-      (compilers, cache, sources, classpath, target, options, s) => {
+    (compilers, cacheDirectory, unidocSources, unidocClasspath, unidocDirectory, scalacOptions in doc, apiMappings in (Compile, doc), streams) map {
+      (compilers, cache, sources, classpath, target, options, api, s) => {
         val scaladoc = new Scaladoc(100, compilers.scalac)
-        scaladoc.cached(cache / "unidoc", "main", sources, classpath, target, options, s.log)
+        val opts1 = options ++ Opts.doc.externalAPI(api)
+        scaladoc.cached(cache / "unidoc", "main", sources, classpath, target, opts1, s.log)
         target
       }
     }