diff --git a/cli/command/image/build.go b/cli/command/image/build.go
index 40b246c5c4..1b03038b7c 100644
--- a/cli/command/image/build.go
+++ b/cli/command/image/build.go
@@ -265,7 +265,7 @@ func runBuild(dockerCli command.Cli, options buildOptions) error {
 		}
 
 		// And canonicalize dockerfile name to a platform-independent one
-		relDockerfile = archive.CanonicalTarNameForPath(relDockerfile)
+		relDockerfile = filepath.ToSlash(relDockerfile)
 
 		excludes = build.TrimBuildFilesFromExcludes(excludes, relDockerfile, options.dockerfileFromStdin())
 		buildCtx, err = archive.TarWithOptions(contextDir, &archive.TarOptions{
diff --git a/cli/command/image/build/dockerignore.go b/cli/command/image/build/dockerignore.go
index 38cde094ac..c7360d402e 100644
--- a/cli/command/image/build/dockerignore.go
+++ b/cli/command/image/build/dockerignore.go
@@ -32,6 +32,9 @@ func TrimBuildFilesFromExcludes(excludes []string, dockerfile string, dockerfile
 	if keep, _ := fileutils.Matches(".dockerignore", excludes); keep {
 		excludes = append(excludes, "!.dockerignore")
 	}
+
+	// canonicalize dockerfile name to be platform-independent.
+	dockerfile = filepath.ToSlash(dockerfile)
 	if keep, _ := fileutils.Matches(dockerfile, excludes); keep && !dockerfileFromStdin {
 		excludes = append(excludes, "!"+dockerfile)
 	}