diff --git a/cmd/puppeth/genesis_test.go b/cmd/puppeth/genesis_test.go
index 83e7383605..f128da24f9 100644
--- a/cmd/puppeth/genesis_test.go
+++ b/cmd/puppeth/genesis_test.go
@@ -18,7 +18,6 @@ package main
 
 import (
 	"encoding/json"
-	"fmt"
 	"io/ioutil"
 	"reflect"
 	"strings"
@@ -61,7 +60,7 @@ func TestAlethSturebyConverter(t *testing.T) {
 		got := strings.Split(c.Sdump(spec), "\n")
 		for i := 0; i < len(exp) && i < len(got); i++ {
 			if exp[i] != got[i] {
-				fmt.Printf("got: %v\nexp: %v\n", exp[i], got[i])
+				t.Logf("got: %v\nexp: %v\n", exp[i], got[i])
 			}
 		}
 	}
@@ -102,7 +101,7 @@ func TestParitySturebyConverter(t *testing.T) {
 		got := strings.Split(c.Sdump(spec), "\n")
 		for i := 0; i < len(exp) && i < len(got); i++ {
 			if exp[i] != got[i] {
-				fmt.Printf("got: %v\nexp: %v\n", exp[i], got[i])
+				t.Logf("got: %v\nexp: %v\n", exp[i], got[i])
 			}
 		}
 	}