diff --git a/src/gloss/parser.gleam b/src/gloss/parser.gleam
index 5ec1616..11776d0 100644
--- a/src/gloss/parser.gleam
+++ b/src/gloss/parser.gleam
@@ -1,6 +1,7 @@
 import gleam/result
 import gleam/list
 import gleam/regex
+import gleam/string
 import gloss/utils/fs
 import gloss/models/database.{type Database}
 import gloss/parser/common
@@ -38,7 +39,10 @@ pub fn parse_posts(db: Database, path: String) -> Result(Database, ParseError) {
     )
 
   let filenames =
-    list.filter(filenames, fn(file) { regex.check(filename_regex, file) })
+    list.filter(filenames, fn(file) {
+      string.ends_with(file, common.filename_postfix)
+      && regex.check(filename_regex, file)
+    })
 
   use posts <- result.try(
     result.all(
@@ -63,19 +67,21 @@ pub fn parse_pages(db: Database, path: String) -> Result(Database, ParseError) {
     |> result.map_error(fn(err) { FileError(path, err) }),
   )
 
-  use pages <- result.try(
-    result.all(
-      list.map(filenames, fn(file) {
-        use contents <- result.try(
-          fs.read_file(path <> "/" <> file)
-          |> result.map_error(fn(err) { FileError(file, err) }),
-        )
+  use pages <- result.try(result.all(
+    filenames
+    |> list.filter(fn(filename) {
+      string.ends_with(filename, common.filename_postfix)
+    })
+    |> list.map(fn(file) {
+      use contents <- result.try(
+        fs.read_file(path <> "/" <> file)
+        |> result.map_error(fn(err) { FileError(file, err) }),
+      )
 
-        page.parse(file, contents)
-        |> result.map_error(fn(err) { PostParseError(file, err) })
-      }),
-    ),
-  )
+      page.parse(file, contents)
+      |> result.map_error(fn(err) { PostParseError(file, err) })
+    }),
+  ))
 
   Ok(list.fold(pages, db, database.add_page))
 }
diff --git a/src/gloss/parser/common.gleam b/src/gloss/parser/common.gleam
index 2f5ddeb..1e2acd6 100644
--- a/src/gloss/parser/common.gleam
+++ b/src/gloss/parser/common.gleam
@@ -4,6 +4,8 @@ import gleam/list
 import gleam/bool
 import gloss/models/header.{type Header}
 
+pub const filename_postfix = ".md"
+
 const header_separator = ":"
 
 pub type ParseError {
diff --git a/src/gloss/parser/page.gleam b/src/gloss/parser/page.gleam
index 6517106..2b9ad99 100644
--- a/src/gloss/parser/page.gleam
+++ b/src/gloss/parser/page.gleam
@@ -4,14 +4,17 @@ import gleam/list
 import gloss/models/page.{type Page, Page}
 import gloss/parser/common.{type ParseError, EmptyFile, HeaderMissing, try}
 
-const filename_postfix = ".md"
-
 pub fn parse(filename: String, contents: String) -> Result(Page, ParseError) {
   let lines = string.split(contents, "\n")
 
   use title <- try(list.first(lines), EmptyFile)
   use rest <- try(list.rest(lines), HeaderMissing)
-  let slug = parse_slug(filename)
+  let slug =
+    string.slice(
+      filename,
+      0,
+      string.length(filename) - string.length(common.filename_postfix),
+    )
 
   let #(headers, body) =
     list.split_while(rest, fn(line) { !string.is_empty(line) })
@@ -21,15 +24,3 @@ pub fn parse(filename: String, contents: String) -> Result(Page, ParseError) {
 
   Ok(Page(title: title, slug: slug, headers: headers, content: body))
 }
-
-fn parse_slug(filename: String) -> String {
-  case string.ends_with(filename, filename_postfix) {
-    True ->
-      string.slice(
-        filename,
-        0,
-        string.length(filename) - string.length(filename_postfix),
-      )
-    False -> filename
-  }
-}
diff --git a/src/gloss/parser/post.gleam b/src/gloss/parser/post.gleam
index df55058..4a50b63 100644
--- a/src/gloss/parser/post.gleam
+++ b/src/gloss/parser/post.gleam
@@ -20,8 +20,6 @@ pub const filename_regex = "^\\d{4}-\\d\\d-\\d\\d-.*\\.md$"
 
 const filename_separator = "-"
 
-const filename_postfix = ".md"
-
 const tag_separator = ","
 
 const split_re = "<!--\\s*SPLIT\\s*-->"
@@ -31,15 +29,12 @@ type FilenameMeta {
 }
 
 pub fn parse(filename: String, contents: String) -> Result(Post, ParseError) {
-  let filename = case string.ends_with(filename, filename_postfix) {
-    True ->
-      string.slice(
-        filename,
-        0,
-        string.length(filename) - string.length(filename_postfix),
-      )
-    False -> filename
-  }
+  let filename =
+    string.slice(
+      filename,
+      0,
+      string.length(filename) - string.length(common.filename_postfix),
+    )
   use meta <- result.try(parse_filename_meta(filename))
 
   let lines = string.split(contents, "\n")