@@ -408,14 +408,6 @@ func (b *buildFile) CmdAdd(args string) error {

 			sums = b.context.GetSums()

 		)

-		// Has tarsum strips the '.' and './', we put it back for comparaison.

-		for file, sum := range sums {

-			if len(file) == 0 || file[0] != '.' && file[0] != '/' {

-				delete(sums, file)

-				sums["./"+file] = sum

-			}

-		}

-

 		if fi, err := os.Stat(path.Join(b.contextPath, origPath)); err != nil {

 			return err

 		} else if fi.IsDir() {

@@ -432,7 +424,13 @@ func (b *buildFile) CmdAdd(args string) error {

 			hasher.Write([]byte(strings.Join(subfiles, ",")))

 			hash = "dir:" + hex.EncodeToString(hasher.Sum(nil))

 		} else {

-			hash = "file:" + sums[origPath]

+			if origPath[0] == '/' && len(origPath) > 1 {

+				origPath = origPath[1:]

+			}

+			origPath = strings.TrimPrefix(origPath, "./")

+			if h, ok := sums[origPath]; ok {

+				hash = "file:" + h

+			}

 		}

 		b.config.Cmd = []string{"/bin/sh", "-c", fmt.Sprintf("#(nop) ADD %s in %s", hash, dest)}

 		hit, err := b.probeCache()