diff --git a/directories.go b/directories.go
index 09f6fb9..d07d7c8 100644
--- a/directories.go
+++ b/directories.go
@@ -3,6 +3,7 @@ package owl
 import (
 	"os"
 	"path/filepath"
+	"strings"
 )
 
 func dirExists(path string) bool {
@@ -38,3 +39,24 @@ func walkDir(path string) []string {
 	})
 	return files
 }
+
+func toDirectoryName(name string) string {
+	name = strings.ToLower(strings.ReplaceAll(name, " ", "-"))
+	// remove all non-alphanumeric characters
+	name = strings.Map(func(r rune) rune {
+		if r >= 'a' && r <= 'z' {
+			return r
+		}
+		if r >= 'A' && r <= 'Z' {
+			return r
+		}
+		if r >= '0' && r <= '9' {
+			return r
+		}
+		if r == '-' {
+			return r
+		}
+		return -1
+	}, name)
+	return name
+}
diff --git a/user.go b/user.go
index 3de6939..181e75c 100644
--- a/user.go
+++ b/user.go
@@ -142,8 +142,7 @@ func (user User) GetPost(id string) (Post, error) {
 }
 
 func (user User) CreateNewPost(title string, draft bool) (Post, error) {
-	timestamp := time.Now().UTC().Unix()
-	folder_name := fmt.Sprintf("%d-%s", timestamp, title)
+	folder_name := toDirectoryName(title)
 	post_dir := path.Join(user.Dir(), "public", folder_name)
 
 	// if post already exists, add -n to the end of the name
@@ -151,7 +150,7 @@ func (user User) CreateNewPost(title string, draft bool) (Post, error) {
 	for {
 		if dirExists(post_dir) {
 			i++
-			folder_name = fmt.Sprintf("%d-%s-%d", timestamp, title, i)
+			folder_name = toDirectoryName(fmt.Sprintf("%s-%d", title, i))
 			post_dir = path.Join(user.Dir(), "public", folder_name)
 		} else {
 			break
diff --git a/user_test.go b/user_test.go
index 6b4e1a0..e833e6e 100644
--- a/user_test.go
+++ b/user_test.go
@@ -317,3 +317,11 @@ func TestAvatarSetIfFileExist(t *testing.T) {
 		t.Error("Avatar should not be empty")
 	}
 }
+
+func TestPostNameIllegalFileName(t *testing.T) {
+	user := getTestUser()
+	_, err := user.CreateNewPost("testpost?///", false)
+	if err != nil {
+		t.Error("Should not have failed")
+	}
+}