diff --git a/api/client.go b/api/client.go
index f9174dd46..719c605fb 100644
--- a/api/client.go
+++ b/api/client.go
@@ -16,7 +16,6 @@ package api
 
 import (
 	"context"
-	"fmt"
 	"io/ioutil"
 	"net"
 	"net/http"
@@ -43,13 +42,6 @@ func (w *ErrorAPI) Err() error {
 }
 
 func (w *ErrorAPI) Error() string {
-	if w == nil {
-		fmt.Println("w nil")
-	} else {
-		if w.err == nil {
-			fmt.Println("w err nil")
-		}
-	}
 	return w.err.Error()
 }
 
diff --git a/api/client_test.go b/api/client_test.go
index 9e8e8a1a5..7877e6a99 100644
--- a/api/client_test.go
+++ b/api/client_test.go
@@ -16,7 +16,6 @@ package api
 import (
 	"context"
 	"encoding/json"
-	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -155,7 +154,6 @@ func TestDoGetFallback(t *testing.T) {
 	// Do a post, and ensure that the post succeeds.
 	_, b, err := DoGetFallback(client, context.TODO(), u, v)
 	if err != nil {
-		fmt.Println(err)
 		t.Fatalf("Error doing local request: %v", err)
 	}
 	resp := &testResponse{}
diff --git a/api/prometheus/v1/api_test.go b/api/prometheus/v1/api_test.go
index 140ccbc73..91b12dfd1 100644
--- a/api/prometheus/v1/api_test.go
+++ b/api/prometheus/v1/api_test.go
@@ -27,6 +27,7 @@ import (
 
 	"github.com/prometheus/client_golang/api"
 	"github.com/prometheus/common/model"
+	"github.com/prometheus/tsdb/testutil"
 )
 
 type apiTest struct {
@@ -883,9 +884,7 @@ func TestAPIClientDo(t *testing.T) {
 			}
 
 			if test.expectedWarnings != nil {
-				if !reflect.DeepEqual(test.expectedWarnings, err.Warnings()) {
-					t.Errorf("expected warnings %v, actual=%v", test.expectedWarnings, err.Warnings())
-				}
+				testutil.Equals(t, test.expectedWarnings, err.Warnings(), "expected warnings %v, actual=%v", test.expectedWarnings, err.Warnings())
 			} else {
 				if err.Warnings() != nil {
 					t.Errorf("Unexpected warnings: %v", err.Warnings())