diff --git a/file.go b/file.go
index d637d08..aa58a21 100644
--- a/file.go
+++ b/file.go
@@ -1,6 +1,9 @@
 package main
 
 import (
+	"crypto/sha256"
+	"encoding/base64"
+	"io"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -37,3 +40,18 @@ func moveButDontOvewrite(path string, targetPath string) {
 		num++
 	}
 }
+
+func calculateHash(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	h := sha256.New()
+	if _, err := io.Copy(h, f); err != nil {
+		return "", err
+	}
+
+	return base64.RawStdEncoding.EncodeToString(h.Sum(nil)), nil
+}
diff --git a/filesmap.go b/filesmap.go
new file mode 100644
index 0000000..fb96a92
--- /dev/null
+++ b/filesmap.go
@@ -0,0 +1,67 @@
+package main
+
+import "os"
+
+// FilesMap is a struct for listing files by Size and Hash to search for duplicates
+type FilesMap struct {
+	FilesBySize map[int64]map[string][]string
+}
+
+// Add a file to the Map and calculate hash on demand
+func (fm *FilesMap) Add(path string, info os.FileInfo) error {
+	if info.IsDir() {
+		return nil
+	}
+
+	fileInfo := path
+
+	filesByHash := fm.FilesBySize[info.Size()]
+
+	// first file with same size
+	// => create new map for size
+	if filesByHash == nil {
+		filesByHash = map[string][]string{}
+		fm.FilesBySize[info.Size()] = filesByHash
+		filesByHash[""] = []string{fileInfo}
+		return nil
+	}
+
+	// second file with same size
+	// => calculate hashes for all entries
+	if _, hasEmptyHash := filesByHash[""]; hasEmptyHash {
+		err := appendByFileHash(filesByHash, fileInfo)
+		err2 := appendByFileHash(filesByHash, filesByHash[""][0])
+
+		delete(filesByHash, "")
+
+		if err != nil {
+			return err
+		}
+
+		return err2
+	}
+
+	// for later files always append by hash
+	return appendByFileHash(filesByHash, fileInfo)
+}
+
+func appendByFileHash(filesByHash map[string][]string, fileInfo string) error {
+	hash, err := calculateHash(fileInfo)
+
+	if err != nil {
+		return err
+	}
+
+	if _, ok := filesByHash[hash]; ok {
+		filesByHash[hash] = append(filesByHash[hash], fileInfo)
+	} else {
+		filesByHash[hash] = []string{fileInfo}
+	}
+	return nil
+}
+
+func newFilesMap() *FilesMap {
+	return &FilesMap{
+		FilesBySize: map[int64]map[string][]string{},
+	}
+}
diff --git a/main.go b/main.go
index 8e90677..558365e 100644
--- a/main.go
+++ b/main.go
@@ -2,12 +2,9 @@ package main
 
 import (
 	"bufio"
-	"crypto/sha256"
-	"encoding/base64"
 	"encoding/json"
 	"flag"
 	"fmt"
-	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -142,82 +139,3 @@ func printConfiguration() {
 	fmt.Println()
 	fmt.Println()
 }
-
-// FilesMap is a struct for listing files by Size and Hash to search for duplicates
-type FilesMap struct {
-	FilesBySize map[int64]map[string][]string
-}
-
-// Add a file to the Map and calculate hash on demand
-func (fm *FilesMap) Add(path string, info os.FileInfo) error {
-	if info.IsDir() {
-		return nil
-	}
-
-	fileInfo := path
-
-	filesByHash := fm.FilesBySize[info.Size()]
-
-	// first file with same size
-	// => create new map for size
-	if filesByHash == nil {
-		filesByHash = map[string][]string{}
-		fm.FilesBySize[info.Size()] = filesByHash
-		filesByHash[""] = []string{fileInfo}
-		return nil
-	}
-
-	// second file with same size
-	// => calculate hashes for all entries
-	if _, hasEmptyHash := filesByHash[""]; hasEmptyHash {
-		err := appendByFileHash(filesByHash, fileInfo)
-		err2 := appendByFileHash(filesByHash, filesByHash[""][0])
-
-		delete(filesByHash, "")
-
-		if err != nil {
-			return err
-		}
-
-		return err2
-	}
-
-	// for later files always append by hash
-	return appendByFileHash(filesByHash, fileInfo)
-}
-
-func appendByFileHash(filesByHash map[string][]string, fileInfo string) error {
-	hash, err := calculateHash(fileInfo)
-
-	if err != nil {
-		return err
-	}
-
-	if _, ok := filesByHash[hash]; ok {
-		filesByHash[hash] = append(filesByHash[hash], fileInfo)
-	} else {
-		filesByHash[hash] = []string{fileInfo}
-	}
-	return nil
-}
-
-func newFilesMap() *FilesMap {
-	return &FilesMap{
-		FilesBySize: map[int64]map[string][]string{},
-	}
-}
-
-func calculateHash(path string) (string, error) {
-	f, err := os.Open(path)
-	if err != nil {
-		return "", err
-	}
-	defer f.Close()
-
-	h := sha256.New()
-	if _, err := io.Copy(h, f); err != nil {
-		return "", err
-	}
-
-	return base64.RawStdEncoding.EncodeToString(h.Sum(nil)), nil
-}