diff --git a/dub.sdl b/dub.sdl
index 6fbf8f7..8a13fa1 100644
--- a/dub.sdl
+++ b/dub.sdl
@@ -17,7 +17,7 @@ configuration "unittest" {
 	dependency "unit-threaded" version="*"
 	targetType "executable"
 	mainSourceFile "tests/ut/ut_runner.d"
-	dflags "-dip1000"
+	dflags "-dip1000" "-dip1008"
 	sourcePaths "source" "tests/ut"
 	importPaths "source" "tests/ut"
 }
@@ -25,7 +25,7 @@ configuration "unittest-release" {
 	dependency "unit-threaded" version="*"
 	targetType "executable"
 	mainSourceFile "tests/ut/ut_runner.d"
-	dflags "-dip1000" "-g"
+	dflags "-dip1000" "-g" "-dip1008"
 	sourcePaths "source" "tests/ut"
 	importPaths "source" "tests/ut"
   # buildOptions "unittests"  "optimize"  "inline"
diff --git a/source/concurrency/error.d b/source/concurrency/error.d
index 9324a46..908c29f 100644
--- a/source/concurrency/error.d
+++ b/source/concurrency/error.d
@@ -19,6 +19,8 @@ Throwable clone(Throwable t) nothrow @safe {
     return new ThrowableClone!RangeError(t.info, r.file, r.line, r.next);
   if (auto e = cast(Error)t)
     return new ThrowableClone!Error(t.info, t.msg, t.file, t.line, t.next);
+  if (auto e = cast(Exception)t)
+    return new ThrowableClone!Exception(t.info, t.msg, t.file, t.line, t.next);
   return new ThrowableClone!Throwable(t.info, t.msg, t.file, t.line, t.next);
 }
 
@@ -53,3 +55,21 @@ class ClonedTraceInfo : Throwable.TraceInfo {
     return buf;
   }
 }
+
+Exception unscopeException(scope Exception e) @trusted nothrow {
+  if (e.refcount == 0) {
+    //TODO: what if exception is allocated on stack or TLS?
+    return cast(Exception)e;
+  }
+
+  return cast(Exception)e.clone();
+}
+
+Throwable unscopeException(scope Throwable e) @trusted nothrow {
+  if (e.refcount == 0) {
+    //TODO: what if exception is allocated on stack or TLS?
+    return cast(Throwable)e;
+  }
+
+  return e.clone();
+}
diff --git a/source/concurrency/nursery.d b/source/concurrency/nursery.d
index 8c8b0b1..bb9781c 100644
--- a/source/concurrency/nursery.d
+++ b/source/concurrency/nursery.d
@@ -105,7 +105,8 @@ class Nursery : StopSource {
           try {
             localReceiver.setValue();
           } catch (Exception e) {
-            localReceiver.setError(e);
+            import concurrency.error;
+            localReceiver.setError(e.unscopeException);
           }
         }
       }
diff --git a/source/concurrency/operations/onerror.d b/source/concurrency/operations/onerror.d
index dfd56a4..08dca6f 100644
--- a/source/concurrency/operations/onerror.d
+++ b/source/concurrency/operations/onerror.d
@@ -34,7 +34,8 @@ private struct OnErrorReceiver(Value, SideEffect, Receiver) {
       try
         sideEffect(e);
       catch (Exception e2) {
-        receiver.setError(() @trusted { return Throwable.chainTogether(e2, e); } ());
+        import concurrency.error;
+        receiver.setError(() @trusted { return Throwable.chainTogether(e2.unscopeException, e); } ());
         return;
       }
     }
diff --git a/source/concurrency/operations/onresult.d b/source/concurrency/operations/onresult.d
index e474164..ac9c81f 100644
--- a/source/concurrency/operations/onresult.d
+++ b/source/concurrency/operations/onresult.d
@@ -43,8 +43,9 @@ private struct OnResultReceiver(Value, SideEffect, Receiver) {
       try {
         sideEffect(Result!(Value)(ex));
       } catch (Exception e2) {
+        import concurrency.error;
         return receiver.setError(() @trusted {
-            return Throwable.chainTogether(e2, e);
+            return Throwable.chainTogether(e2.unscopeException, e);
           }());
       } catch (Throwable t) {
         return receiver.setError(t);
diff --git a/source/concurrency/operations/repeat.d b/source/concurrency/operations/repeat.d
index d42cf9a..5f74d90 100644
--- a/source/concurrency/operations/repeat.d
+++ b/source/concurrency/operations/repeat.d
@@ -42,7 +42,8 @@ private struct RepeatOp(Receiver, Sender) {
     try {
       reset();
     } catch (Exception e) {
-      receiver.setError(e);
+      import concurrency.error;
+      receiver.setError(e.unscopeException);
     }
   }
   private void reset() @trusted scope {
diff --git a/source/concurrency/operations/retry.d b/source/concurrency/operations/retry.d
index b45d4a0..8288aa6 100644
--- a/source/concurrency/operations/retry.d
+++ b/source/concurrency/operations/retry.d
@@ -59,7 +59,8 @@ private struct RetryReceiver(Receiver, Sender, Logic) {
         // From what I gathered that is what libunifex does
         sender.connectHeap(this).start();
       } catch (Exception e) {
-        receiver.setError(e);
+        import concurrency.error;
+        receiver.setError(e.unscopeException);
       }
     }
   }
diff --git a/source/concurrency/operations/toshared.d b/source/concurrency/operations/toshared.d
index 96e9c78..7f8f35b 100644
--- a/source/concurrency/operations/toshared.d
+++ b/source/concurrency/operations/toshared.d
@@ -51,7 +51,8 @@ class SharedSender(Sender, Scheduler, ResetLogic resetLogic) if (models!(Sender,
             try {
               localState.op = sender.connect(SharedSenderReceiver!(Sender, Scheduler, resetLogic)(&state, scheduler));
             } catch (Exception e) {
-              state.process!(resetLogic)(InternalValue(e));
+              import concurrency.error;
+              state.process!(resetLogic)(InternalValue(e.unscopeException));
             }
             localState.op.start();
           } else {
@@ -158,10 +159,12 @@ private struct SharedSenderOp(Sender, Scheduler, ResetLogic resetLogic, Receiver
             /// this onValue can sometimes be called immediately,
             /// leaving no room to set cb.dispose...
             cb.dispose();
-            receiver.setError(e);
+            import concurrency.error;
+            receiver.setError(e.unscopeException);
           }
         }, (Throwable e){
-          receiver.setError(e);
+          import concurrency.error;
+          receiver.setError(e.unscopeException);
         }, (Done d){
           receiver.setDone();
         });
diff --git a/source/concurrency/receiver.d b/source/concurrency/receiver.d
index 56ed378..259a7bf 100644
--- a/source/concurrency/receiver.d
+++ b/source/concurrency/receiver.d
@@ -72,7 +72,8 @@ void setValueOrError(Receiver)(auto ref Receiver receiver) @safe {
     try {
       receiver.setValue();
     } catch (Exception e) {
-      receiver.setError(e);
+      import concurrency.error;
+      receiver.setError(e.unscopeException);
     }
   }
 }
@@ -85,7 +86,8 @@ void setValueOrError(Receiver, T)(auto ref Receiver receiver, auto ref T value)
     try {
       receiver.setValue(value);
     } catch (Exception e) {
-      receiver.setError(e);
+      import concurrency.error;
+      receiver.setError(e.unscopeException);
     }
   }
 }
diff --git a/source/concurrency/scheduler.d b/source/concurrency/scheduler.d
index 9dfca8b..27f1969 100644
--- a/source/concurrency/scheduler.d
+++ b/source/concurrency/scheduler.d
@@ -77,7 +77,8 @@ struct SchedulerAdapter(Worker) {
         try {
           worker.schedule(cast(VoidDelegate)()=>receiver.setValueOrError());
         } catch (Exception e) {
-          receiver.setError(e);
+          import concurrency.error;
+          receiver.setError(e.unscopeException);
         }
       }
     }
@@ -135,7 +136,8 @@ struct ScheduleAfterOp(Worker, Receiver) {
     try {
       timer = worker.addTimer(cast(void delegate(TimerTrigger) @safe shared)&trigger, dur);
     } catch (Exception e) {
-      receiver.setError(e);
+      import concurrency.error;
+      receiver.setError(e.unscopeException);
       return;
     }
 
diff --git a/source/concurrency/sender.d b/source/concurrency/sender.d
index bbb6865..74c831d 100644
--- a/source/concurrency/sender.d
+++ b/source/concurrency/sender.d
@@ -137,7 +137,8 @@ struct JustFromSender(Fun) {
         try {
           set();
         } catch (Exception e) {
-          receiver.setError(e);
+          import concurrency.error;
+          receiver.setError(e.unscopeException);
         }
       }
     }
@@ -463,14 +464,15 @@ struct PromiseSenderOp(T, Receiver) {
       // calling the receiver's termination functions.
       if (cb)
         cb.dispose();
-      value.match!((Sender.ValueRep v){
+      value.match!((Sender.ValueRep v) @safe {
+          import concurrency.error;
           try {
             static if (is(Sender.Value == void))
               receiver.setValue();
             else
               receiver.setValue(v);
           } catch (Exception e) {
-            receiver.setError(e);
+            receiver.setError(e.unscopeException);
           }
         }, (Throwable e){
           receiver.setError(e);
diff --git a/source/concurrency/stream/package.d b/source/concurrency/stream/package.d
index fb0d51d..30e38d7 100644
--- a/source/concurrency/stream/package.d
+++ b/source/concurrency/stream/package.d
@@ -120,14 +120,16 @@ auto intervalStream(Duration duration, bool emitAtStart = false) {
         }
         op.load();
       } catch (Exception e) {
-        op.receiver.setError(e);
+        import concurrency.error;
+        op.receiver.setError(e.unscopeException);
       }
     }
     void setDone() @safe nothrow {
       op.receiver.setDone();
     }
     void setError(Throwable t) @safe nothrow {
-      op.receiver.setError(t);
+      import concurrency.error;
+      op.receiver.setError(t.unscopeException);
     }
     auto getStopToken() @safe {
       return op.receiver.getStopToken();
@@ -165,7 +167,8 @@ auto intervalStream(Duration duration, bool emitAtStart = false) {
         }
         load();
       } catch (Exception e) {
-        receiver.setError(e);
+        import concurrency.error;
+        receiver.setError(e.unscopeException);
       }
     }
     private void load() @trusted nothrow {
@@ -173,7 +176,8 @@ auto intervalStream(Duration duration, bool emitAtStart = false) {
         op = receiver.getScheduler().scheduleAfter(duration).connect(ItemReceiver!(typeof(this))(&this));
         op.start();
       } catch (Exception e) {
-        receiver.setError(e);
+        import concurrency.error;
+        receiver.setError(e.unscopeException);
       }
     }
   }
@@ -294,9 +298,10 @@ shared struct SharedStream(T) {
           try {
             dg(element);
           } catch (Exception e) {
+            import concurrency.error;
             source.remove(&this.onItem);
             cb.dispose();
-            receiver.setError(e);
+            receiver.setError(e.unscopeException);
           }
         }
       }
diff --git a/source/concurrency/stream/stream.d b/source/concurrency/stream/stream.d
index fb98f54..6d3860e 100644
--- a/source/concurrency/stream/stream.d
+++ b/source/concurrency/stream/stream.d
@@ -118,7 +118,8 @@ template loopStream(E) {
           try {
             t.loop(dg, receiver.getStopToken);
           } catch (Exception e) {
-            receiver.setError(e);
+            import concurrency.error;
+            receiver.setError(e.unscopeException);
           }
           if (receiver.getStopToken().isStopRequested)
             receiver.setDone();
diff --git a/source/concurrency/stream/throttling.d b/source/concurrency/stream/throttling.d
index ab0e38f..be00276 100644
--- a/source/concurrency/stream/throttling.d
+++ b/source/concurrency/stream/throttling.d
@@ -102,9 +102,10 @@ template ThrottleStreamOp(Stream, ThrottleEmitLogic emitLogic, ThrottleTimerLogi
           dg();
           return true;
         } catch (Exception e) {
+          import concurrency.error;
           with (flags.lock(ThrottleFlags.doneOrError_produced)) {
             if ((oldState & ThrottleFlags.doneOrError_produced) == 0) {
-              throwable = e;
+              throwable = e.unscopeException;
             }
             release();
             process(newState);
@@ -136,9 +137,10 @@ template ThrottleStreamOp(Stream, ThrottleEmitLogic emitLogic, ThrottleTimerLogi
           dg(t);
           return true;
         } catch (Exception e) {
+          import concurrency.error;
           with (flags.lock(ThrottleFlags.doneOrError_produced)) {
             if ((oldState & ThrottleFlags.doneOrError_produced) == 0) {
-              throwable = e;
+              throwable = e.unscopeException;
             }
             release();
             process(newState);
@@ -198,7 +200,8 @@ template ThrottleStreamOp(Stream, ThrottleEmitLogic emitLogic, ThrottleTimerLogi
               else
                 dg();
             } catch (Exception e) {
-              receiver.setError(e);
+              import concurrency.error;
+              receiver.setError(e.unscopeException);
               return;
             }
           }
diff --git a/source/concurrency/syncwait.d b/source/concurrency/syncwait.d
index 000816d..c67a6b2 100644
--- a/source/concurrency/syncwait.d
+++ b/source/concurrency/syncwait.d
@@ -32,7 +32,8 @@ package struct SyncWaitReceiver2(Value) {
   }
 
   void setError(Throwable e) nothrow @safe {
-    state.throwable = e;
+    import concurrency.error;
+    state.throwable = e.unscopeException;
     state.worker.stop();
   }
   static if (is(Value == void))
diff --git a/source/concurrency/thread.d b/source/concurrency/thread.d
index 93cabe0..c93c346 100644
--- a/source/concurrency/thread.d
+++ b/source/concurrency/thread.d
@@ -353,7 +353,8 @@ struct ThreadSender {
       try {
         receiver.setValue();
       } catch (Exception e) {
-        receiver.setError(e);
+        import concurrency.error;
+        receiver.setError(e.unscopeException);
       } catch (Throwable t) {
         receiver.setError(t.clone());
       }
@@ -435,7 +436,8 @@ private struct TaskPoolSender {
       try {
         receiver.setValue();
       } catch (Exception e) {
-        receiver.setError(e);
+        import concurrency.error;
+        receiver.setError(e.unscopeException);
       } catch (Throwable t) {
         receiver.setError(t.clone);
       }
@@ -454,7 +456,8 @@ private struct TaskPoolSender {
       try {
         pool.put(myTask);
       } catch (Exception e) {
-        myTask.args[0].setError(e);
+        import concurrency.error;
+        myTask.args[0].setError(e.unscopeException);
       }
     }
   }
diff --git a/tests/ut/concurrency/operations.d b/tests/ut/concurrency/operations.d
index 8e4ab84..5e571bf 100644
--- a/tests/ut/concurrency/operations.d
+++ b/tests/ut/concurrency/operations.d
@@ -72,6 +72,7 @@ struct OutOfBandValueSender(T) {
 
 @("race.exception.double")
 @safe unittest {
+  // TODO: this is flaky. Find another way.
   auto slow = ThreadSender().then(() shared @trusted { Thread.sleep(50.msecs); throw new Exception("Slow"); });
   auto fast = ThreadSender().then(() shared { throw new Exception("Fast"); });
   race(slow, fast).syncWait.assumeOk.shouldThrowWithMessage("Fast");
diff --git a/tests/ut/concurrency/stream.d b/tests/ut/concurrency/stream.d
index c17966a..c0b83a6 100644
--- a/tests/ut/concurrency/stream.d
+++ b/tests/ut/concurrency/stream.d
@@ -604,11 +604,11 @@ unittest {
 
 @("flatmap.concat.error")
 @safe unittest {
-  import concurrency.sender : just, ErrorSender;
+  import concurrency.sender : just, ThrowingSender;
   import concurrency.operations : via;
 
   [1,2,3].arrayStream
-    .flatMapConcat((int i) => ErrorSender())
+    .flatMapConcat((int i) => ThrowingSender())
     .collect(()shared{})
     .syncWait
     .assumeOk
@@ -659,11 +659,11 @@ unittest {
 
 @("flatmap.latest.error")
 @safe unittest {
-  import concurrency.sender : just, ErrorSender;
+  import concurrency.sender : just, ThrowingSender;
   import concurrency.operations : via;
 
   [1,2,3].arrayStream
-    .flatMapLatest((int i) => ErrorSender())
+    .flatMapLatest((int i) => ThrowingSender())
     .collect(()shared{})
     .syncWait
     .assumeOk