diff --git a/core/jvm/src/test/scala/fs2/StreamPerformanceSpec.scala b/core/jvm/src/test/scala/fs2/StreamPerformanceSpec.scala
index c27aa5ce92..0ec22cc253 100644
--- a/core/jvm/src/test/scala/fs2/StreamPerformanceSpec.scala
+++ b/core/jvm/src/test/scala/fs2/StreamPerformanceSpec.scala
@@ -31,12 +31,24 @@ class StreamPerformanceSpec extends Fs2Spec {
       }
     }}
 
+    "left-associated eval_() ++ flatMap 1" - { Ns.foreach { N =>
+      N.toString in {
+        runLog((1 until N).map(emit).foldLeft(emit(0).covary[IO])((acc,a) => acc flatMap { _ => eval(IO {()}) flatMap { _ =>  a }})) shouldBe Vector(N-1)
+      }
+    }}
+
     "right-associated flatMap 1" - { Ns.foreach { N =>
       N.toString in {
         runLog((1 until N).map(emit).reverse.foldLeft(emit(0))((acc,a) => a flatMap { _ => acc })) shouldBe Vector(0)
       }
     }}
 
+    "right-associated eval_() ++ flatMap 1" - { Ns.foreach { N =>
+      N.toString in {
+        runLog((1 until N).map(emit).reverse.foldLeft(emit(0).covary[IO])((acc,a) => a flatMap { _ => eval(IO {()}) flatMap { _=> acc } })) shouldBe Vector(0)
+      }
+    }}
+
     "left-associated flatMap 2" - { Ns.foreach { N =>
       N.toString in {
         runLog((1 until N).map(emit).foldLeft(emit(0) ++ emit(1) ++ emit(2))(