diff --git a/internal/engine/inputloader_test.go b/internal/engine/inputloader_test.go
index 38bf483..9e231ef 100644
--- a/internal/engine/inputloader_test.go
+++ b/internal/engine/inputloader_test.go
@@ -80,6 +80,10 @@ func TestInputLoaderNewOrchestraClientFailure(t *testing.T) {
 
 type InputLoaderBrokenOrchestraClient struct{}
 
+func (InputLoaderBrokenOrchestraClient) CheckIn(ctx context.Context, config model.CheckInConfig) (*model.CheckInInfo, error) {
+	return nil, io.EOF
+}
+
 func (InputLoaderBrokenOrchestraClient) FetchPsiphonConfig(ctx context.Context) ([]byte, error) {
 	return nil, io.EOF
 }
diff --git a/internal/engine/internal/mockable/mockable.go b/internal/engine/internal/mockable/mockable.go
index 1ce50af..032e24d 100644
--- a/internal/engine/internal/mockable/mockable.go
+++ b/internal/engine/internal/mockable/mockable.go
@@ -162,6 +162,8 @@ var _ torx.Session = &Session{}
 // ExperimentOrchestraClient is the experiment's view of
 // a client for querying the OONI orchestra.
 type ExperimentOrchestraClient struct {
+	MockableCheckInInfo              *model.CheckInInfo
+	MockableCheckInErr               error
 	MockableFetchPsiphonConfigResult []byte
 	MockableFetchPsiphonConfigErr    error
 	MockableFetchTorTargetsResult    map[string]model.TorTarget
@@ -170,6 +172,12 @@ type ExperimentOrchestraClient struct {
 	MockableFetchURLListErr          error
 }
 
+// CheckIn implements ExperimentOrchestraClient.CheckIn.
+func (c ExperimentOrchestraClient) CheckIn(
+	ctx context.Context, config model.CheckInConfig) (*model.CheckInInfo, error) {
+	return c.MockableCheckInInfo, c.MockableCheckInErr
+}
+
 // FetchPsiphonConfig implements ExperimentOrchestraClient.FetchPsiphonConfig
 func (c ExperimentOrchestraClient) FetchPsiphonConfig(
 	ctx context.Context) ([]byte, error) {
diff --git a/internal/engine/model/experiment.go b/internal/engine/model/experiment.go
index 18e8add..18e5f32 100644
--- a/internal/engine/model/experiment.go
+++ b/internal/engine/model/experiment.go
@@ -8,8 +8,17 @@ import (
 // ExperimentOrchestraClient is the experiment's view of
 // a client for querying the OONI orchestra API.
 type ExperimentOrchestraClient interface {
+	// CheckIn calls the check-in API.
+	CheckIn(ctx context.Context, config CheckInConfig) (*CheckInInfo, error)
+
+	// FetchPsiphonConfig returns psiphon config from the API.
 	FetchPsiphonConfig(ctx context.Context) ([]byte, error)
+
+	// FetchTorTargets returns tor targets from the API.
 	FetchTorTargets(ctx context.Context, cc string) (map[string]TorTarget, error)
+
+	// FetchURLList returns URLs from the API.
+	// This method is deprecated and will be removed soon.
 	FetchURLList(ctx context.Context, config URLListConfig) ([]URLInfo, error)
 }
 
diff --git a/pkg/oonimkall/task_integration_test.go b/pkg/oonimkall/task_integration_test.go
index 9848a54..f8d1081 100644
--- a/pkg/oonimkall/task_integration_test.go
+++ b/pkg/oonimkall/task_integration_test.go
@@ -315,7 +315,7 @@ func TestMaxRuntime(t *testing.T) {
 	// In case there are further timeouts, e.g. in the sessionresolver, the
 	// time used by the experiment will be much more. This is for example the
 	// case in https://github.com/ooni/probe-engine/issues/1005.
-	if time.Now().Sub(begin) > 10*time.Second {
+	if time.Since(begin) > 10*time.Second {
 		t.Fatal("expected shorter runtime")
 	}
 }