diff --git a/actions/download_action.go b/actions/download_action.go
index d82c4ea..97665f5 100644
--- a/actions/download_action.go
+++ b/actions/download_action.go
@@ -63,7 +63,7 @@ func (d *DownloadAction) validateUrl() (*url.URL, error) {
 	case "http", "https":
 		// Supported scheme
 	default:
-		return url, fmt.Errorf("Unsupported URL is provided: '%s'", url.String())
+		return url, fmt.Errorf("unsupported URL provided: '%s'", url.String())
 	}
 
 	return url, nil
@@ -77,7 +77,7 @@ func (d *DownloadAction) validateFilename(context *debos.DebosContext, url *url.
 		filename = path.Base(d.Filename)
 	}
 	if len(filename) == 0 || filename == "." || filename == "/" {
-		return "", fmt.Errorf("Incorrect filename is provided for '%s'", d.Url)
+		return "", fmt.Errorf("incorrect filename provided for '%s'", d.Url)
 	}
 	filename = path.Join(context.Scratchdir, filename)
 	return filename, nil
@@ -104,7 +104,7 @@ func (d *DownloadAction) Verify(context *debos.DebosContext) error {
 	var filename string
 
 	if len(d.Name) == 0 {
-		return fmt.Errorf("Property 'name' is mandatory for download action\n")
+		return fmt.Errorf("property 'name' is mandatory for download action")
 	}
 
 	url, err := d.validateUrl()
@@ -144,7 +144,7 @@ func (d *DownloadAction) Run(context *debos.DebosContext) error {
 			return err
 		}
 	default:
-		return fmt.Errorf("Unsupported URL is provided: '%s'", url.String())
+		return fmt.Errorf("unsupported URL provided: '%s'", url.String())
 	}
 
 	if d.Unpack == true {
diff --git a/actions/filesystem_deploy_action.go b/actions/filesystem_deploy_action.go
index c2e54f2..c0b9b8f 100644
--- a/actions/filesystem_deploy_action.go
+++ b/actions/filesystem_deploy_action.go
@@ -56,14 +56,14 @@ func NewFilesystemDeployAction() *FilesystemDeployAction {
 
 func (fd *FilesystemDeployAction) setupFSTab(context *debos.DebosContext) error {
 	if context.ImageFSTab.Len() == 0 {
-		return errors.New("Fstab not generated, missing image-partition action?")
+		return errors.New("fstab not generated, missing image-partition action?")
 	}
 
 	log.Print("Setting up /etc/fstab")
 
 	err := os.MkdirAll(path.Join(context.Rootdir, "etc"), 0755)
 	if err != nil {
-		return fmt.Errorf("Couldn't create etc in image: %v", err)
+		return fmt.Errorf("couldn't create etc in image: %v", err)
 	}
 
 	fstab := path.Join(context.Rootdir, "etc/fstab")
@@ -71,13 +71,13 @@ func (fd *FilesystemDeployAction) setupFSTab(context *debos.DebosContext) error
 	defer f.Close()
 
 	if err != nil {
-		return fmt.Errorf("Couldn't open /etc/fstab: %v", err)
+		return fmt.Errorf("couldn't open /etc/fstab: %v", err)
 	}
 
 	_, err = io.Copy(f, &context.ImageFSTab)
 
 	if err != nil {
-		return fmt.Errorf("Couldn't write /etc/fstab: %v", err)
+		return fmt.Errorf("couldn't write /etc/fstab: %v", err)
 	}
 
 	return nil
@@ -90,7 +90,7 @@ func (fd *FilesystemDeployAction) setupKernelCmdline(context *debos.DebosContext
 
 	err := os.MkdirAll(path.Join(context.Rootdir, "etc", "kernel"), 0755)
 	if err != nil {
-		return fmt.Errorf("Couldn't create etc/kernel in image: %v", err)
+		return fmt.Errorf("couldn't create etc/kernel in image: %v", err)
 	}
 	path := path.Join(context.Rootdir, "etc/kernel/cmdline")
 	current, _ := ioutil.ReadFile(path)
@@ -98,7 +98,7 @@ func (fd *FilesystemDeployAction) setupKernelCmdline(context *debos.DebosContext
 	defer f.Close()
 
 	if err != nil {
-		return fmt.Errorf("Couldn't open /etc/kernel/cmdline: %v", err)
+		return fmt.Errorf("couldn't open /etc/kernel/cmdline: %v", err)
 	}
 
 	cmdline = append(cmdline, strings.TrimSpace(string(current)))
@@ -110,7 +110,7 @@ func (fd *FilesystemDeployAction) setupKernelCmdline(context *debos.DebosContext
 
 	_, err = f.WriteString(strings.Join(cmdline, " ") + "\n")
 	if err != nil {
-		return fmt.Errorf("Couldn't write /etc/kernel/cmdline: %v", err)
+		return fmt.Errorf("couldn't write /etc/kernel/cmdline: %v", err)
 	}
 
 	return nil
diff --git a/actions/image_partition_action.go b/actions/image_partition_action.go
index 4df2443..5433b25 100644
--- a/actions/image_partition_action.go
+++ b/actions/image_partition_action.go
@@ -279,7 +279,7 @@ func (i *ImagePartitionAction) generateFSTab(context *debos.DebosContext) error
 			continue
 		}
 		if m.part.FSUUID == "" {
-			return fmt.Errorf("Missing fs UUID for partition %s!?!", m.part.Name)
+			return fmt.Errorf("missing fs UUID for partition %s", m.part.Name)
 		}
 
 		fs_passno := 0
@@ -312,7 +312,7 @@ func (i *ImagePartitionAction) generateKernelRoot(context *debos.DebosContext) e
 	for _, m := range i.Mountpoints {
 		if m.Mountpoint == "/" {
 			if m.part.FSUUID == "" {
-				return errors.New("No fs UUID for root partition !?!")
+				return errors.New("no fs UUID for root partition")
 			}
 			context.ImageKernelRoot = fmt.Sprintf("root=UUID=%s", m.part.FSUUID)
 			break
@@ -458,7 +458,7 @@ func (i ImagePartitionAction) formatPartition(p *Partition, context debos.DebosC
 	if p.FS != "none" && p.FSUUID == "" {
 		uuid, err := exec.Command("blkid", "-o", "value", "-s", "UUID", "-p", "-c", "none", path).Output()
 		if err != nil {
-			return fmt.Errorf("Failed to get uuid: %s", err)
+			return fmt.Errorf("failed to get uuid: %s", err)
 		}
 		p.FSUUID = strings.TrimSpace(string(uuid[:]))
 	}
@@ -470,12 +470,12 @@ func (i *ImagePartitionAction) PreNoMachine(context *debos.DebosContext) error {
 	imagePath := path.Join(context.Artifactdir, i.ImageName)
 	img, err := os.OpenFile(imagePath, os.O_WRONLY|os.O_CREATE, 0666)
 	if err != nil {
-		return fmt.Errorf("Couldn't open image file: %v", err)
+		return fmt.Errorf("couldn't open image file: %v", err)
 	}
 
 	err = img.Truncate(i.size)
 	if err != nil {
-		return fmt.Errorf("Couldn't resize image file: %v", err)
+		return fmt.Errorf("couldn't resize image file: %v", err)
 	}
 
 	img.Close()
@@ -492,7 +492,7 @@ func (i *ImagePartitionAction) PreNoMachine(context *debos.DebosContext) error {
 	}
 
 	if err != nil {
-		return fmt.Errorf("Failed to setup loop device: %v", err)
+		return fmt.Errorf("failed to setup loop device: %v", err)
 	}
 
 	// go-losetup doesn't provide a way to change the loop device sector size
@@ -804,7 +804,7 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 		// Just check if it contains correct value
 		_, err := units.FromHumanSize(i.GptGap)
 		if err != nil {
-			return fmt.Errorf("Failed to parse GPT offset: %s", i.GptGap)
+			return fmt.Errorf("failed to parse image size: %s", i.GptGap)
 		}
 	}
 
@@ -813,12 +813,12 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 		case "gpt":
 			_, err := uuid.Parse(i.DiskID)
 			if err != nil {
-				return fmt.Errorf("Incorrect disk GUID %s", i.DiskID)
+				return fmt.Errorf("incorrect disk GUID %s", i.DiskID)
 			}
 		case "msdos":
 			_, err := hex.DecodeString(i.DiskID)
 			if err != nil || len(i.DiskID) != 8 {
-				return fmt.Errorf("Incorrect disk ID %s, should be 32-bit hexadecimal number", i.DiskID)
+				return fmt.Errorf("incorrect disk ID %s, should be 32-bit hexadecimal number", i.DiskID)
 			}
 			// Add 0x prefix
 			i.DiskID = "0x" + i.DiskID
@@ -832,13 +832,13 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 		p.number = num
 		num++
 		if p.Name == "" {
-			return fmt.Errorf("Partition without a name")
+			return fmt.Errorf("partition without a name")
 		}
 
 		// check for duplicate partition names
 		for j := idx + 1; j < len(i.Partitions); j++ {
 			if i.Partitions[j].Name == p.Name {
-				return fmt.Errorf("Partition %s already exists", p.Name)
+				return fmt.Errorf("partition %s already exists", p.Name)
 			}
 		}
 
@@ -847,20 +847,20 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 			case "btrfs", "ext2", "ext3", "ext4", "xfs":
 				_, err := uuid.Parse(p.FSUUID)
 				if err != nil {
-					return fmt.Errorf("Incorrect UUID %s", p.FSUUID)
+					return fmt.Errorf("incorrect UUID %s", p.FSUUID)
 				}
 			case "fat", "fat12", "fat16", "fat32", "msdos", "vfat":
 				_, err := hex.DecodeString(p.FSUUID)
 				if err != nil || len(p.FSUUID) != 8 {
-					return fmt.Errorf("Incorrect UUID %s, should be 32-bit hexadecimal number", p.FSUUID)
+					return fmt.Errorf("incorrect UUID %s, should be 32-bit hexadecimal number", p.FSUUID)
 				}
 			default:
-				return fmt.Errorf("Setting the UUID is not supported for filesystem %s", p.FS)
+				return fmt.Errorf("setting the UUID is not supported for filesystem %s", p.FS)
 			}
 		}
 
 		if i.PartitionType != "gpt" && p.PartLabel != "" {
-			return fmt.Errorf("Can only set partition partlabel on GPT filesystem")
+			return fmt.Errorf("can only set partition partlabel on GPT filesystem")
 		}
 
 		if len(p.PartUUID) > 0 {
@@ -868,10 +868,10 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 			case "gpt":
 				_, err := uuid.Parse(p.PartUUID)
 				if err != nil {
-					return fmt.Errorf("Incorrect partition UUID %s", p.PartUUID)
+					return fmt.Errorf("incorrect partition UUID %s", p.PartUUID)
 				}
 			default:
-				return fmt.Errorf("Setting the partition UUID is not supported for %s", i.PartitionType)
+				return fmt.Errorf("setting the partition UUID is not supported for %s", i.PartitionType)
 			}
 		}
 
@@ -891,19 +891,19 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 		for _, bitStr := range p.PartAttrs {
 			bit, err := strconv.ParseInt(bitStr, 0, 0)
 			if err != nil || bit < 0 || bit > 2 && bit < 48 || bit > 63 {
-				return fmt.Errorf("Partition attribute bit '%s' outside of valid range (0-2, 48-63)", bitStr)
+				return fmt.Errorf("partition attribute bit '%s' outside of valid range (0-2, 48-63)", bitStr)
 			}
 		}
 
 		if p.Start == "" {
-			return fmt.Errorf("Partition %s missing start", p.Name)
+			return fmt.Errorf("partition %s missing start", p.Name)
 		}
 		if p.End == "" {
-			return fmt.Errorf("Partition %s missing end", p.Name)
+			return fmt.Errorf("partition %s missing end", p.Name)
 		}
 
 		if p.FS == "" {
-			return fmt.Errorf("Partition %s missing fs type", p.Name)
+			return fmt.Errorf("partition %s missing fs type", p.Name)
 		}
 
 		if p.FSLabel == "" {
@@ -939,7 +939,7 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 		// check for duplicate mountpoints
 		for j := idx + 1; j < len(i.Mountpoints); j++ {
 			if i.Mountpoints[j].Mountpoint == m.Mountpoint {
-				return fmt.Errorf("Mountpoint %s already exists", m.Mountpoint)
+				return fmt.Errorf("mountpoint %s already exists", m.Mountpoint)
 			}
 		}
 
@@ -951,11 +951,11 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 			}
 		}
 		if m.part == nil {
-			return fmt.Errorf("Couldn't find partition for %s", m.Mountpoint)
+			return fmt.Errorf("couldn't find partition for %s", m.Mountpoint)
 		}
 
 		if strings.ToLower(m.part.FS) == "none" {
-			return fmt.Errorf("Cannot mount %s: filesystem not present", m.Mountpoint)
+			return fmt.Errorf("cannot mount %s: filesystem not present", m.Mountpoint)
 		}
 	}
 
@@ -971,7 +971,7 @@ func (i *ImagePartitionAction) Verify(context *debos.DebosContext) error {
 
 	size, err := getSizeValueFunc(i.ImageSize)
 	if err != nil {
-		return fmt.Errorf("Failed to parse image size: %s", i.ImageSize)
+		return fmt.Errorf("failed to parse image size: %s", i.ImageSize)
 	}
 
 	i.size = size
diff --git a/actions/overlay_action.go b/actions/overlay_action.go
index 9478a66..4632445 100644
--- a/actions/overlay_action.go
+++ b/actions/overlay_action.go
@@ -53,7 +53,7 @@ func (overlay *OverlayAction) Run(context *debos.DebosContext) error {
 	if len(overlay.Origin) > 0 {
 		var found bool
 		if origin, found = context.Origin(overlay.Origin); !found {
-			return fmt.Errorf("Origin not found '%s'", overlay.Origin)
+			return fmt.Errorf("origin not found '%s'", overlay.Origin)
 		}
 	}
 
diff --git a/actions/pack_action.go b/actions/pack_action.go
index 2cf3a76..51f6ef1 100644
--- a/actions/pack_action.go
+++ b/actions/pack_action.go
@@ -67,7 +67,7 @@ func (pf *PackAction) Verify(context *debos.DebosContext) error {
 		possibleTypes = append(possibleTypes, key)
 	}
 
-	return fmt.Errorf("Option 'compression' has an unsupported type: `%s`. Possible types are %s.",
+	return fmt.Errorf("option 'compression' has an unsupported type: `%s`; possible types are %s",
 		pf.Compression, strings.Join(possibleTypes, ", "))
 }
 
diff --git a/actions/pacstrap_action.go b/actions/pacstrap_action.go
index e0eb9d2..b018104 100644
--- a/actions/pacstrap_action.go
+++ b/actions/pacstrap_action.go
@@ -35,13 +35,13 @@ func (d *PacstrapAction) listOptionFiles(context *debos.DebosContext) ([]string,
 	files := []string{}
 
 	if d.Config == "" {
-		return nil, fmt.Errorf("No config file set")
+		return nil, fmt.Errorf("no config file set")
 	}
 	d.Config = debos.CleanPathAt(d.Config, context.RecipeDir)
 	files = append(files, d.Config)
 
 	if d.Mirror == "" {
-		return nil, fmt.Errorf("No mirror file set")
+		return nil, fmt.Errorf("no mirror file set")
 	}
 	d.Mirror = debos.CleanPathAt(d.Mirror, context.RecipeDir)
 	files = append(files, d.Mirror)
@@ -110,13 +110,13 @@ func (d *PacstrapAction) Run(context *debos.DebosContext) error {
 	// Even if we did, blindly copying it might not be a good idea.
 	cmdline := []string{"pacman-key", "--init"}
 	if err := (debos.Command{}.Run("pacman-key", cmdline...)); err != nil {
-		return fmt.Errorf("Couldn't init pacman keyring: %v", err)
+		return fmt.Errorf("couldn't init pacman keyring: %v", err)
 	}
 
 	// When there's no explicit keyring suite we populate all available
 	cmdline = []string{"pacman-key", "--populate"}
 	if err := (debos.Command{}.Run("pacman-key", cmdline...)); err != nil {
-		return fmt.Errorf("Couldn't populate pacman keyring: %v", err)
+		return fmt.Errorf("couldn't populate pacman keyring: %v", err)
 	}
 
 	// Run pacstrap
diff --git a/actions/raw_action.go b/actions/raw_action.go
index cdd6616..c09eab2 100644
--- a/actions/raw_action.go
+++ b/actions/raw_action.go
@@ -61,7 +61,7 @@ func (raw *RawAction) checkDeprecatedSyntax() error {
 		log.Printf("Usage of 'source' and 'path' properties is deprecated.")
 		log.Printf("Please use 'origin' and 'source' properties.")
 		if len(raw.Origin) > 0 {
-			return errors.New("Can't mix 'origin' and 'path'(deprecated option) properties")
+			return errors.New("can't mix 'origin' and 'path'(deprecated option) properties")
 		}
 		if len(raw.Source) == 0 {
 			return errors.New("'source' and 'path' properties can't be empty")
@@ -89,13 +89,13 @@ func (raw *RawAction) Verify(context *debos.DebosContext) error {
 func (raw *RawAction) Run(context *debos.DebosContext) error {
 	origin, found := context.Origin(raw.Origin)
 	if !found {
-		return fmt.Errorf("Origin `%s` doesn't exist\n", raw.Origin)
+		return fmt.Errorf("origin `%s` doesn't exist", raw.Origin)
 	}
 	s := path.Join(origin, raw.Source)
 	content, err := ioutil.ReadFile(s)
 
 	if err != nil {
-		return fmt.Errorf("Failed to read %s", s)
+		return fmt.Errorf("failed to read %s", s)
 	}
 
 	var devicePath string
@@ -108,7 +108,7 @@ func (raw *RawAction) Run(context *debos.DebosContext) error {
 		}
 
 		if devicePath == "" {
-			return fmt.Errorf("Failed to find partition named %s", raw.Partition)
+			return fmt.Errorf("failed to find partition named %s", raw.Partition)
 		}
 	} else {
 		devicePath = context.Image
@@ -116,7 +116,7 @@ func (raw *RawAction) Run(context *debos.DebosContext) error {
 
 	target, err := os.OpenFile(devicePath, os.O_WRONLY, 0)
 	if err != nil {
-		return fmt.Errorf("Failed to open %s: %v", devicePath, err)
+		return fmt.Errorf("failed to open %s: %v", devicePath, err)
 	}
 	defer target.Close()
 
@@ -130,7 +130,7 @@ func (raw *RawAction) Run(context *debos.DebosContext) error {
 		}
 		offset, err = strconv.ParseInt(offs, 0, 64)
 		if err != nil {
-			return fmt.Errorf("Couldn't parse offset %v", err)
+			return fmt.Errorf("couldn't parse offset %v", err)
 		}
 
 		if sector {
@@ -140,12 +140,12 @@ func (raw *RawAction) Run(context *debos.DebosContext) error {
 
 	bytes, err := target.WriteAt(content, offset)
 	if bytes != len(content) {
-		return fmt.Errorf("Couldn't write complete data %v", err)
+		return fmt.Errorf("couldn't write complete data %v", err)
 	}
 
 	err = target.Sync()
 	if err != nil {
-		return fmt.Errorf("Couldn't sync content %v", err)
+		return fmt.Errorf("couldn't sync content %v", err)
 	}
 
 	return nil
diff --git a/actions/recipe.go b/actions/recipe.go
index 3c3c570..0ae1d47 100644
--- a/actions/recipe.go
+++ b/actions/recipe.go
@@ -155,7 +155,7 @@ func (y *YamlAction) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	case "recipe":
 		y.Action = &RecipeAction{}
 	default:
-		return fmt.Errorf("Unknown action: %v", aux.Action)
+		return fmt.Errorf("unknown action: %v", aux.Action)
 	}
 
 	err = unmarshal(y.Action)
diff --git a/actions/recipe_action.go b/actions/recipe_action.go
index 2e8629c..14c0644 100644
--- a/actions/recipe_action.go
+++ b/actions/recipe_action.go
@@ -77,7 +77,7 @@ func (recipe *RecipeAction) Verify(context *debos.DebosContext) error {
 	}
 
 	if recipe.context.Architecture != recipe.Actions.Architecture {
-		return fmt.Errorf("Expect architecture '%s' but got '%s'", context.Architecture, recipe.Actions.Architecture)
+		return fmt.Errorf("expected architecture '%s' but got '%s'", context.Architecture, recipe.Actions.Architecture)
 	}
 
 	for _, a := range recipe.Actions.Actions {
diff --git a/actions/recipe_test.go b/actions/recipe_test.go
index 42bfb9c..0a4a324 100644
--- a/actions/recipe_test.go
+++ b/actions/recipe_test.go
@@ -72,7 +72,7 @@ architecture: arm64
 actions:
   - action: test_unknown_action
 `,
-			"Unknown action: test_unknown_action",
+			"unknown action: test_unknown_action",
 		},
 		// Test if 'architecture' property absence
 		{`
@@ -147,7 +147,7 @@ architecture: arm64
 actions:
   - action: {{ sector 42 }}
 `,
-		"Unknown action: 42s",
+		"unknown action: 42s",
 	}
 	runTest(t, testSector)
 }
@@ -281,7 +281,7 @@ actions:
     recipe: armhf.yaml
 `,
 			recipeArmhf,
-			"Expect architecture 'amd64' but got 'armhf'",
+			"expected architecture 'amd64' but got 'armhf'",
 			"", // Do not expect parse failure
 		},
 		{
diff --git a/actions/run_action.go b/actions/run_action.go
index 6f12fec..cb68de5 100644
--- a/actions/run_action.go
+++ b/actions/run_action.go
@@ -65,11 +65,11 @@ type RunAction struct {
 
 func (run *RunAction) Verify(context *debos.DebosContext) error {
 	if run.PostProcess && run.Chroot {
-		return errors.New("Cannot run postprocessing in the chroot")
+		return errors.New("cannot run postprocessing in the chroot")
 	}
 
 	if run.Script == "" && run.Command == "" {
-		return errors.New("Script and Command both cannot be empty")
+		return errors.New("need to set 'script' or 'command'")
 	}
 	return nil
 }
diff --git a/actions/unpack_action.go b/actions/unpack_action.go
index daee91b..789e183 100644
--- a/actions/unpack_action.go
+++ b/actions/unpack_action.go
@@ -47,7 +47,7 @@ type UnpackAction struct {
 func (pf *UnpackAction) Verify(context *debos.DebosContext) error {
 
 	if len(pf.Origin) == 0 && len(pf.File) == 0 {
-		return fmt.Errorf("Filename can't be empty. Please add 'file' and/or 'origin' property.")
+		return fmt.Errorf("filename can't be empty. Please add 'file' and/or 'origin' property")
 	}
 
 	archive, err := debos.NewArchive(pf.File)
@@ -56,7 +56,7 @@ func (pf *UnpackAction) Verify(context *debos.DebosContext) error {
 	}
 	if len(pf.Compression) > 0 {
 		if archive.Type() != debos.Tar {
-			return fmt.Errorf("Option 'compression' is supported for Tar archives only.")
+			return fmt.Errorf("option 'compression' is supported for Tar archives only")
 		}
 		if err := archive.AddOption("tarcompression", pf.Compression); err != nil {
 			return fmt.Errorf("'%s': %s", pf.File, err)
@@ -74,7 +74,7 @@ func (pf *UnpackAction) Run(context *debos.DebosContext) error {
 		//Trying to get a filename from origins first
 		origin, found = context.Origin(pf.Origin)
 		if !found {
-			return fmt.Errorf("Origin not found '%s'", pf.Origin)
+			return fmt.Errorf("origin not found '%s'", pf.Origin)
 		}
 	} else {
 		origin = context.Artifactdir
diff --git a/archiver.go b/archiver.go
index fded175..8e46c19 100644
--- a/archiver.go
+++ b/archiver.go
@@ -150,23 +150,23 @@ func (tar *ArchiveTar) AddOption(key, value interface{}) error {
 		// expect a slice
 		options, ok := value.([]string)
 		if !ok {
-			return fmt.Errorf("Wrong type for value")
+			return fmt.Errorf("wrong type for value")
 		}
 		tar.options["taroptions"] = options
 
 	case "tarcompression":
 		compression, ok := value.(string)
 		if !ok {
-			return fmt.Errorf("Wrong type for value")
+			return fmt.Errorf("wrong type for value")
 		}
 		option := tarOptions(compression)
 		if len(option) == 0 {
-			return fmt.Errorf("Compression '%s' is not supported", compression)
+			return fmt.Errorf("compression '%s' is not supported", compression)
 		}
 		tar.options["tarcompression"] = compression
 
 	default:
-		return fmt.Errorf("Option '%v' is not supported for tar archive type", key)
+		return fmt.Errorf("option '%v' is not supported for tar archive type", key)
 	}
 	return nil
 }
@@ -228,7 +228,7 @@ func NewArchive(file string, arcType ...ArchiveType) (Archive, error) {
 	case Deb:
 		archive = Archive{&ArchiveDeb{ArchiveBase: common}}
 	default:
-		return archive, fmt.Errorf("Unsupported archive '%s'", file)
+		return archive, fmt.Errorf("unsupported archive '%s'", file)
 	}
 	return archive, nil
 }
diff --git a/archiver_test.go b/archiver_test.go
index 4383dfb..5f34ecf 100644
--- a/archiver_test.go
+++ b/archiver_test.go
@@ -14,7 +14,7 @@ func TestBase(t *testing.T) {
 	// New archive
 	// Expect Tar by default
 	_, err := debos.NewArchive("test.base", 0)
-	assert.EqualError(t, err, "Unsupported archive 'test.base'")
+	assert.EqualError(t, err, "unsupported archive 'test.base'")
 
 	// Test base
 	archive := debos.ArchiveBase{}
@@ -64,7 +64,7 @@ func TestTar_default(t *testing.T) {
 
 	// Add wrong option
 	err = archive.AddOption("someoption", "somevalue")
-	assert.EqualError(t, err, "Option 'someoption' is not supported for tar archive type")
+	assert.EqualError(t, err, "option 'someoption' is not supported for tar archive type")
 }
 
 // Check supported compression types
@@ -91,13 +91,13 @@ func TestTar_compression(t *testing.T) {
 	}
 	// Check of unsupported compression type
 	err = archive.AddOption("tarcompression", "fake")
-	assert.EqualError(t, err, "Compression 'fake' is not supported")
+	assert.EqualError(t, err, "compression 'fake' is not supported")
 
 	// Pass incorrect type
 	err = archive.AddOption("taroptions", nil)
-	assert.EqualError(t, err, "Wrong type for value")
+	assert.EqualError(t, err, "wrong type for value")
 	err = archive.AddOption("tarcompression", nil)
-	assert.EqualError(t, err, "Wrong type for value")
+	assert.EqualError(t, err, "wrong type for value")
 }
 
 func TestDeb(t *testing.T) {
diff --git a/commands.go b/commands.go
index f0c5c0f..5963d80 100644
--- a/commands.go
+++ b/commands.go
@@ -332,7 +332,7 @@ func newQemuHelper(c Command) (*qemuHelper, error) {
 			q.qemusrc = "/usr/bin/qemu-sh4-static"
 		}
 	default:
-		return nil, fmt.Errorf("Don't know qemu for architecture %s", c.Architecture)
+		return nil, fmt.Errorf("unsupported qemu architecture %s", c.Architecture)
 	}
 
 	if q.qemusrc != "" {
diff --git a/filesystem.go b/filesystem.go
index 43cf8c8..4206dbc 100644
--- a/filesystem.go
+++ b/filesystem.go
@@ -69,18 +69,18 @@ func CopyTree(sourcetree, desttree string) error {
 		case 0:
 			err := CopyFile(p, target, info.Mode())
 			if err != nil {
-				return fmt.Errorf("Failed to copy file %s: %w", p, err)
+				return fmt.Errorf("failed to copy file %s: %w", p, err)
 			}
 		case os.ModeDir:
 			os.Mkdir(target, info.Mode())
 		case os.ModeSymlink:
 			link, err := os.Readlink(p)
 			if err != nil {
-				return fmt.Errorf("Failed to read symlink %s: %w", suffix, err)
+				return fmt.Errorf("failed to read symlink %s: %w", suffix, err)
 			}
 			os.Symlink(link, target)
 		default:
-			return fmt.Errorf("File %s with mode %v not handled", p, info.Mode())
+			return fmt.Errorf("file %s with mode %v not handled", p, info.Mode())
 		}
 
 		return nil
@@ -106,7 +106,7 @@ func RestrictedPath(prefix, dest string) (string, error) {
 		return "", err
 	}
 	if !strings.HasPrefix(destination, prefix) {
-		return "", fmt.Errorf("The resulting path points outside of prefix '%s': '%s'\n", prefix, destination)
+		return "", fmt.Errorf("resulting path points outside of prefix '%s': '%s'", prefix, destination)
 	}
 	return destination, nil
 }
diff --git a/net.go b/net.go
index 989c90d..fe4ebaa 100644
--- a/net.go
+++ b/net.go
@@ -17,7 +17,7 @@ func DownloadHttpUrl(url, filename string) error {
 	// Check if file object already exists.
 	fi, err := os.Stat(filename)
 	if !os.IsNotExist(err) && !fi.Mode().IsRegular() {
-		return fmt.Errorf("Failed to download '%s': '%s' exists and it is not a regular file\n", url, filename)
+		return fmt.Errorf("failed to download '%s': '%s' exists and it is not a regular file", url, filename)
 	}
 
 	resp, err := http.Get(url)
@@ -27,7 +27,7 @@ func DownloadHttpUrl(url, filename string) error {
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		return fmt.Errorf("Url '%s' returned status code %d (%s)\n", url, resp.StatusCode, http.StatusText(resp.StatusCode))
+		return fmt.Errorf("url '%s' returned status code %d (%s)", url, resp.StatusCode, http.StatusText(resp.StatusCode))
 	}
 
 	// Output file
diff --git a/os.go b/os.go
index 67abba1..0762cd0 100644
--- a/os.go
+++ b/os.go
@@ -50,7 +50,7 @@ exit 101
 `)
 
 	if _, err := os.Stat(helperFile); os.IsExist(err) {
-		return fmt.Errorf("Policy helper file '%s' exists already", debianPolicyHelper)
+		return fmt.Errorf("policy helper file '%s' exists already", debianPolicyHelper)
 	}
 	if _, err := os.Stat(path.Dir(helperFile)); os.IsNotExist(err) {
 		// do not try to do something if ".../usr/sbin" is not exists