diff --git a/main/actions/src/main/scala/sbt/compiler/Eval.scala b/main/actions/src/main/scala/sbt/compiler/Eval.scala
index e533ac5a2..f41fb9dbe 100644
--- a/main/actions/src/main/scala/sbt/compiler/Eval.scala
+++ b/main/actions/src/main/scala/sbt/compiler/Eval.scala
@@ -348,8 +348,21 @@ final class Eval(optionsNoncp: Seq[String], classpath: Seq[File], mkReporter: Se
 
   val DefaultStartLine = 0
   private[this] def makeModuleName(hash: String): String = "$" + Hash.halve(hash)
-  private[this] def noImports = new EvalImports(Nil, "")
-  private[this] def mkUnit(srcName: String, firstLine: Int, s: String) = new CompilationUnit(new EvalSourceFile(srcName, firstLine, s))
+  private[sbt] def noImports = new EvalImports(Nil, "")
+  private[sbt] def mkUnit(srcName: String, firstLine: Int, s: String) = new CompilationUnit(new EvalSourceFile(srcName, firstLine, s)) {
+    // This is overridden as a workaround for #1181/#1501,
+    // When the compiler reports an error back, the position sometimes comes back with source set to NoSourceFile. 
+    override def error(pos0: Position, msg: String) = {
+      import scala.reflect.internal.util._
+      val pos = pos0 match {
+        case op: OffsetPosition if op.point >= 0 =>
+          if (op.source eq source) op
+          else new OffsetPosition(source, op.point)
+        case _ => pos0
+      }
+      super.error(pos, msg)
+    }
+  }
   private[this] def checkError(label: String) = if (reporter.hasErrors) throw new EvalException(label)
 
   private[this] final class EvalSourceFile(name: String, startLine: Int, contents: String) extends BatchSourceFile(name, contents) {
diff --git a/notes/0.13.6.md b/notes/0.13.6.md
index 22c4a93c0..556fe7530 100644
--- a/notes/0.13.6.md
+++ b/notes/0.13.6.md
@@ -2,6 +2,7 @@
   [856]: https://github.com/sbt/sbt/issues/856
   [1036]: https://github.com/sbt/sbt/pull/1036
   [1059]: https://github.com/sbt/sbt/issues/1059
+  [1181]: https://github.com/sbt/sbt/issues/1181
   [1194]: https://github.com/sbt/sbt/issues/1194
   [1200]: https://github.com/sbt/sbt/issues/1200
   [1213]: https://github.com/sbt/sbt/issues/1213
@@ -96,6 +97,7 @@
 - sbt no longer crashes when run in root directory [#1488][1488] by [@jsuereth][@jsuereth]
 - set no longer removes any `++` scala version setting.  [#856][856]/[#1489][1489] by [@jsuereth][@jsuereth]
 - Fixes `Scope.parseScopedKey`. [#1384][1384] by [@eed3si9n][@eed3si9n]
+- Fixes `build.sbt` errors causing `ArrayIndexOutOfBoundsException` due to invalid source in position. [#1181][1181] by [@eed3si9n][@eed3si9n]
 
 ### enablePlugins/disablePlugins