diff --git a/tasks/src/main/scala/sbt/CompletionService.scala b/tasks/src/main/scala/sbt/CompletionService.scala
index f6fc3a957..88f00a5e8 100644
--- a/tasks/src/main/scala/sbt/CompletionService.scala
+++ b/tasks/src/main/scala/sbt/CompletionService.scala
@@ -17,7 +17,8 @@ import java.util.concurrent.{
   CompletionService => JCompletionService,
   Executor,
   Executors,
-  ExecutorCompletionService
+  ExecutorCompletionService,
+  RejectedExecutionException,
 }
 
 object CompletionService {
@@ -33,7 +34,9 @@ object CompletionService {
       def take() = completion.take().get()
     }
   def submit[T](work: () => T, completion: JCompletionService[T]): () => T = {
-    val future = completion.submit { new Callable[T] { def call = work() } }
+    val future = try completion.submit { new Callable[T] { def call = work() } } catch {
+      case _: RejectedExecutionException => throw Incomplete(None, message = Some("cancelled"))
+    }
     () =>
       future.get()
   }
diff --git a/tasks/src/main/scala/sbt/Execute.scala b/tasks/src/main/scala/sbt/Execute.scala
index f063080ca..c5d16288e 100644
--- a/tasks/src/main/scala/sbt/Execute.scala
+++ b/tasks/src/main/scala/sbt/Execute.scala
@@ -7,8 +7,6 @@
 
 package sbt
 
-import java.util.concurrent.RejectedExecutionException
-
 import sbt.internal.util.ErrorHandling.wideConvert
 import sbt.internal.util.{ DelegatingPMap, IDSet, PMap, RMap, ~> }
 import sbt.internal.util.Types._
@@ -80,19 +78,16 @@ private[sbt] final class Execute[A[_] <: AnyRef](
   def run[T](root: A[T])(implicit strategy: Strategy): Result[T] =
     try { runKeep(root)(strategy)(root) } catch { case i: Incomplete => Inc(i) }
 
-  def runKeep[T](root: A[T])(implicit strategy: Strategy): RMap[A, Result] =
-    try {
-      assert(state.isEmpty, "Execute already running/ran.")
+  def runKeep[T](root: A[T])(implicit strategy: Strategy): RMap[A, Result] = {
+    assert(state.isEmpty, "Execute already running/ran.")
 
-      addNew(root)
-      processAll()
-      assert(results contains root, "No result for root node.")
-      val finalResults = triggers.onComplete(results)
-      progressState = progress.allCompleted(progressState, finalResults)
-      finalResults
-    } catch {
-      case _: RejectedExecutionException => throw Incomplete(None, message = Some("cancelled"))
-    }
+    addNew(root)
+    processAll()
+    assert(results contains root, "No result for root node.")
+    val finalResults = triggers.onComplete(results)
+    progressState = progress.allCompleted(progressState, finalResults)
+    finalResults
+  }
 
   def processAll()(implicit strategy: Strategy): Unit = {
     @tailrec def next(): Unit = {