diff --git a/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ProcCallBackTest.kt b/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ProcCallBackTest.kt
index 76ebba8..55a9faa 100644
--- a/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ProcCallBackTest.kt
+++ b/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ProcCallBackTest.kt
@@ -12,7 +12,6 @@ import arrow.fx.rx2.extensions.observablek.applicativeError.applicativeError
 import arrow.fx.rx2.extensions.observablek.monadDefer.monadDefer
 import arrow.fx.rx2.fix
 import arrow.fx.rx2.value
-import arrow.fx.unsafeRunSync
 import arrow.integrations.retrofit.adapter.mock.ResponseMock
 import arrow.integrations.retrofit.adapter.retrofit.ApiClientTest
 import arrow.integrations.retrofit.adapter.retrofit.retrofit
@@ -35,7 +34,8 @@ class ProcCallBackTest : UnitSpec() {
     "should be able to parse answer with ForIO" {
       createApiClientTest(baseUrl())
         .testCallK()
-        .async(IO.async<Nothing>())
+        .async(IO.async())
+        .fix()
         .unsafeRunSync()
         .unwrapBody(Either.applicativeError())
         .fix()
@@ -64,7 +64,8 @@ class ProcCallBackTest : UnitSpec() {
     "should be able to run a POST with UNIT as response" {
       createApiClientTest(baseUrl())
         .testIOResponsePost()
-        .async(IO.async<Nothing>())
+        .async(IO.async())
+        .fix()
         .unsafeRunSync()
     }
   }
diff --git a/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ResponseCallbackTest.kt b/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ResponseCallbackTest.kt
index ffdc2b4..961620b 100644
--- a/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ResponseCallbackTest.kt
+++ b/arrow-integrations-retrofit-adapter/src/test/kotlin/arrow/integrations/retrofit/adapter/ResponseCallbackTest.kt
@@ -4,7 +4,6 @@ import arrow.core.test.UnitSpec
 import arrow.fx.IO
 import arrow.fx.extensions.io.async.async
 import arrow.fx.fix
-import arrow.fx.unsafeRunSync
 import arrow.integrations.retrofit.adapter.retrofit.ApiClientTest
 import arrow.integrations.retrofit.adapter.retrofit.retrofit
 import io.kotlintest.fail
@@ -24,7 +23,7 @@ class ResponseCallbackTest : UnitSpec() {
     "bad deserialization should return Either.Left" {
       createApiClientTest(baseUrl)
         .testCallK()
-        .async(IO.async<Nothing>())
+        .async(IO.async())
         .fix()
         .attempt()
         .unsafeRunSync()