diff --git a/shortner/normalize_url.go b/shortner/normalize_url.go
index 6e961fa..3befca6 100644
--- a/shortner/normalize_url.go
+++ b/shortner/normalize_url.go
@@ -5,8 +5,8 @@ import (
 	"net/url"
 )
 
-var errURLFileSchema = errors.New("Schema 'file://' not allowed")
-var errURLInvalid = errors.New("Invalid URL")
+var errURLFileSchema = errors.New("schema 'file://' not allowed")
+var errURLInvalid = errors.New("invalid URL")
 
 var slashByte = byte(47)
 var maxLengthURL = 2048
diff --git a/shortner/normalize_url_test.go b/shortner/normalize_url_test.go
index 4b6c9f2..a1e6fe5 100644
--- a/shortner/normalize_url_test.go
+++ b/shortner/normalize_url_test.go
@@ -59,22 +59,22 @@ var examples = []struct {
 	{
 		valid: false,
 		url:   "*$)]+_<?)",
-		error: "Invalid URL",
+		error: "invalid URL",
 	},
 	{
 		valid: false,
 		url:   "",
-		error: "Invalid URL",
+		error: "invalid URL",
 	},
 	{
 		valid: false,
 		url:   "file:///bin/bash",
-		error: "Schema 'file://' not allowed",
+		error: "schema 'file://' not allowed",
 	},
 	{
 		valid: false,
 		url:   "/users/view.php?uid=138495",
-		error: "Invalid URL",
+		error: "invalid URL",
 	},
 	{
 		valid:      true,
@@ -88,7 +88,7 @@ var examples = []struct {
 	{
 		valid: false,
 		url:   "http://long.com/" + strings.Repeat("0", 3000),
-		error: "Invalid URL",
+		error: "invalid URL",
 	},
 }