diff --git a/crit/explore.go b/crit/explore.go
index 6f521d219..93c0f0705 100644
--- a/crit/explore.go
+++ b/crit/explore.go
@@ -328,7 +328,7 @@ func (c *crit) ExploreRss() ([]*RssMap, error) {
 		for _, pagemapEntry := range pagemapImg.Entries[1:] {
 			pagemapData := pagemapEntry.Message.(*pagemap.PagemapEntry)
 			rss := Rss{
-				PhyAddr:  fmt.Sprintf("%x", pagemapData.GetVaddr()),
+				PhyAddr:  strconv.FormatUint(pagemapData.GetVaddr(), 16),
 				PhyPages: int64(pagemapData.GetNrPages()),
 			}
 
@@ -347,7 +347,7 @@ func (c *crit) ExploreRss() ([]*RssMap, error) {
 				}
 
 				rss.Vmas = append(rss.Vmas, &Vma{
-					Addr:  fmt.Sprintf("%x", vmas[vmaIndex].GetStart()),
+					Addr:  strconv.FormatUint(vmas[vmaIndex].GetStart(), 16),
 					Pages: int64(vmas[vmaIndex].GetEnd()-vmas[vmaIndex].GetStart()) >> 12,
 				})
 				// Pages used by a file
diff --git a/features.go b/features.go
index b6d8a45b7..c62e69e06 100644
--- a/features.go
+++ b/features.go
@@ -1,7 +1,7 @@
 package criu
 
 import (
-	"fmt"
+	"errors"
 
 	"github.com/checkpoint-restore/go-criu/v7/rpc"
 )
@@ -38,7 +38,7 @@ func (c *Criu) FeatureCheck(features *rpc.CriuFeatures) (*rpc.CriuFeatures, erro
 	}
 
 	if resp.GetType() != rpc.CriuReqType_FEATURE_CHECK {
-		return nil, fmt.Errorf("unexpected CRIU RPC response")
+		return nil, errors.New("unexpected CRIU RPC response")
 	}
 
 	return features, nil
diff --git a/main.go b/main.go
index 5dd7f192e..6906c9811 100644
--- a/main.go
+++ b/main.go
@@ -230,7 +230,7 @@ func (c *Criu) GetCriuVersion() (int, error) {
 	}
 
 	if resp.GetType() != rpc.CriuReqType_VERSION {
-		return 0, fmt.Errorf("unexpected CRIU RPC response")
+		return 0, errors.New("unexpected CRIU RPC response")
 	}
 
 	version := resp.GetVersion().GetMajorNumber() * 10000
diff --git a/test/crit/main.go b/test/crit/main.go
index 3c97d20cc..84d7eea36 100644
--- a/test/crit/main.go
+++ b/test/crit/main.go
@@ -51,7 +51,7 @@ func recodeImgs(imgs []string) error {
 			return err
 		}
 		defer imgFile.Close()
-		testImg := fmt.Sprintf("%s.test.img", img)
+		testImg := img + ".test.img"
 		testImgFile, err := os.Create(testImg)
 		if err != nil {
 			return err
@@ -115,7 +115,7 @@ func getImgs() ([]string, error) {
 	// "*.test.img", "*.json.img" or "tmp.*.img" files
 	// must be skipped as they are generated by tests
 	criuImg := regexp.MustCompile(`^[^\.]*\.img$`)
-	dir, err := filepath.Glob(fmt.Sprintf("%s/*.img", loopTestImgDir))
+	dir, err := filepath.Glob(loopTestImgDir + "/*.img")
 	if err != nil {
 		return nil, err
 	}