diff --git a/internal/cnf/loader.go b/internal/cnf/loader.go
index 7a669ac..e13de07 100644
--- a/internal/cnf/loader.go
+++ b/internal/cnf/loader.go
@@ -3,7 +3,6 @@ package cnf
 import (
 	"errors"
 	"fmt"
-	"io"
 	"os"
 	"path/filepath"
 )
@@ -50,15 +49,11 @@ func Load(path string) (ConfigurationFormat, error) {
 
 	}
 
-	// 3. open file
-	file, err := os.Open(path)
+	// 4. Try to guess from the content
+	confFormat, err := loadFromContent(path)
 	if err != nil {
 		return nil, err
 	}
-	defer file.Close()
-
-	// 4. Try to guess from the content
-	confFormat = loadFromContent(file)
 	if confFormat == nil {
 		return nil, ErrUnknownFormat
 	}
@@ -84,13 +79,21 @@ func loadFromExtension(ext string) ConfigurationFormat {
 
 }
 
-func loadFromContent(file io.Reader) ConfigurationFormat {
+func loadFromContent(path string) (ConfigurationFormat, error) {
 
-	// extensions ordered by unicity of the language's syntax
-	extensions := []string{".json", ".yaml", ".nginx", ".ini"}
+	// 3. open file
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	// extensions ordered by strictness of the language's syntax
+	extensions := []string{".json", ".nginx", ".yaml", ".ini"}
 
 	// try to load each available extension
 	for _, ext := range extensions {
+		file.Seek(0, 0)
 
 		// load parser
 		c := loadFromExtension(ext)
@@ -101,10 +104,10 @@ func loadFromContent(file io.Reader) ConfigurationFormat {
 		// parse
 		_, err := c.ReadFrom(file)
 		if err == nil {
-			return c
+			return c, nil
 		}
 
 	}
 
-	return nil
+	return nil, ErrUnknownFormat
 }
diff --git a/internal/cnf/parser/nginx/decoder.go b/internal/cnf/parser/nginx/decoder.go
index 8cb9a3e..a6b34b7 100644
--- a/internal/cnf/parser/nginx/decoder.go
+++ b/internal/cnf/parser/nginx/decoder.go
@@ -153,5 +153,4 @@ func (d *Decoder) Decode(v interface{}) error {
 	}
 
 	return nil
-
 }