diff --git a/package.json b/package.json
index 8b76551..35f4793 100644
--- a/package.json
+++ b/package.json
@@ -30,7 +30,8 @@
     "lodash": "^4.17.21",
     "luxon": "^3.2.1",
     "markdown-escape": "^1.1.0",
-    "mustache": "^4.2.0"
+    "mustache": "^4.2.0",
+    "out-of-character": "^1.2.1"
   },
   "devDependencies": {
     "@semantic-release/changelog": "^6.0.1",
diff --git a/src/api.ts b/src/api.ts
index c737840..eceeb05 100644
--- a/src/api.ts
+++ b/src/api.ts
@@ -72,9 +72,9 @@ export enum HighlightType {
 
 export interface Highlight {
   id: string
-  quote: string
-  annotation: string
-  patch: string
+  quote: string | null
+  annotation: string | null
+  patch: string | null
   updatedAt: string
   labels?: Label[]
   type: HighlightType
diff --git a/src/index.ts b/src/index.ts
index 4100166..144a9fd 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -33,6 +33,7 @@ import {
   isBlockPropertiesChanged,
   parseBlockProperties,
   parseDateTime,
+  replaceIllegalChars,
 } from './util'
 
 const isValidCurrentGraph = async (): Promise<boolean> => {
@@ -250,10 +251,8 @@ const fetchOmnivore = async (inBackground = false) => {
       for (const article of articles) {
         if (!isSinglePage) {
           // create a new page for each article
-          pageName = renderPageName(
-            article,
-            pageNameTemplate,
-            preferredDateFormat
+          pageName = replaceIllegalChars(
+            renderPageName(article, pageNameTemplate, preferredDateFormat)
           )
           targetBlockId = (await getOmnivoreBlock(pageName, blockTitle)).uuid
         }
diff --git a/src/settings/template.ts b/src/settings/template.ts
index ecd37fd..83c673e 100644
--- a/src/settings/template.ts
+++ b/src/settings/template.ts
@@ -152,7 +152,7 @@ const createArticleView = (
     dateSaved,
     content: article.content,
     datePublished,
-    note: note?.annotation,
+    note: note?.annotation ?? undefined,
     type: article.pageType,
     rawDatePublished,
     rawDateRead,
@@ -189,7 +189,7 @@ export const renderHighlightContent = (
     highlightUrl: `https://omnivore.app/me/${article.slug}#${highlight.id}`,
     dateHighlighted,
     rawDateHighlighted,
-    note: highlight.annotation,
+    note: highlight.annotation ?? undefined,
     ...functionMap,
   }
   return Mustache.render(template, highlightView)
diff --git a/src/util.ts b/src/util.ts
index b5e19b9..8297ade 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -2,6 +2,7 @@ import { format } from 'date-fns'
 import { diff_match_patch } from 'diff-match-patch'
 import { DateTime } from 'luxon'
 import escape from 'markdown-escape'
+import outOfCharacter from 'out-of-character'
 import { Highlight } from './api'
 
 export interface HighlightPoint {
@@ -11,14 +12,25 @@ export interface HighlightPoint {
 
 export const DATE_FORMAT_W_OUT_SECONDS = "yyyy-MM-dd'T'HH:mm"
 export const DATE_FORMAT = `${DATE_FORMAT_W_OUT_SECONDS}:ss`
-
-export const getHighlightLocation = (patch: string): number => {
+export const REPLACEMENT_CHAR = '-'
+// On Unix-like systems / is reserved and <>:"/\|?* as well as non-printable characters \u0000-\u001F on Windows
+// credit: https://github.com/sindresorhus/filename-reserved-regex
+// eslint-disable-next-line no-control-regex
+export const ILLEGAL_CHAR_REGEX = /[<>:"/\\|?*\u0000-\u001F]/g
+
+export const getHighlightLocation = (patch: string | null): number => {
+  if (!patch) {
+    return 0
+  }
   const dmp = new diff_match_patch()
   const patches = dmp.patch_fromText(patch)
   return patches[0].start1 || 0
 }
 
-export const getHighlightPoint = (patch: string): HighlightPoint => {
+export const getHighlightPoint = (patch: string | null): HighlightPoint => {
+  if (!patch) {
+    return { left: 0, top: 0 }
+  }
   const { bbox } = JSON.parse(patch) as { bbox: number[] }
   if (!bbox || bbox.length !== 4) {
     return { left: 0, top: 0 }
@@ -87,9 +99,13 @@ export const siteNameFromUrl = (originalArticleUrl: string): string => {
 export const delay = (t = 100) => new Promise((r) => setTimeout(r, t))
 
 export const formatHighlightQuote = (
-  quote: string,
+  quote: string | null,
   template: string
 ): string => {
+  if (!quote) {
+    return ''
+  }
+
   if (template.startsWith('>')) {
     // replace all empty lines with blockquote '>' to preserve paragraphs
     quote = quote.replace(/^(?=\n)$|^\s*?\n/gm, '> ')
@@ -162,3 +178,11 @@ export const isBlockPropertiesChanged = (
 export const escapeQuotes = (str: string): string => {
   return str.replace(/"/g, '\\"')
 }
+
+const removeInvisibleChars = (str: string): string => {
+  return outOfCharacter.replace(str)
+}
+
+export const replaceIllegalChars = (str: string): string => {
+  return removeInvisibleChars(str.replace(ILLEGAL_CHAR_REGEX, REPLACEMENT_CHAR))
+}
diff --git a/yarn.lock b/yarn.lock
index 3891435..ab66ce5 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1825,6 +1825,11 @@ color-support@^1.1.3:
   resolved "https://registry.npmjs.org/color-support/-/color-support-1.1.3.tgz"
   integrity sha512-qiBjkpbMLO/HL68y+lh4q0/O1MZFj2RX6X/KmMa3+gJD3z+WwI1ZzDHysvqHGS3mP6mznPckpXmw1nI9cJjyRg==
 
+colorette@1.2.2:
+  version "1.2.2"
+  resolved "https://registry.yarnpkg.com/colorette/-/colorette-1.2.2.tgz#cbcc79d5e99caea2dbf10eb3a26fd8b3e6acfa94"
+  integrity sha512-MKGMzyfeuutC/ZJ1cba9NqcNpfeqMUcYmyF1ZFY6/Cn7CNSAKx6a+s48sqLqyAiZuaP2TcqMhoo+dlwFnVxT9w==
+
 columnify@^1.6.0:
   version "1.6.0"
   resolved "https://registry.npmjs.org/columnify/-/columnify-1.6.0.tgz"
@@ -2639,6 +2644,18 @@ glob-parent@^6.0.1:
   dependencies:
     is-glob "^4.0.3"
 
+glob@7.1.7:
+  version "7.1.7"
+  resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.7.tgz#3b193e9233f01d42d0b3f78294bbeeb418f94a90"
+  integrity sha512-OvD9ENzPLbegENnYP5UUfJIirTg4+XwMWGaQfQTY0JenxNvvIKP3U3/tAQSPIu/lHxXYSZmpXlUHeqAIdKzBLQ==
+  dependencies:
+    fs.realpath "^1.0.0"
+    inflight "^1.0.4"
+    inherits "2"
+    minimatch "^3.0.4"
+    once "^1.3.0"
+    path-is-absolute "^1.0.0"
+
 glob@7.2.0:
   version "7.2.0"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.2.0.tgz#d15535af7732e02e948f4c41628bd910293f6023"
@@ -4077,6 +4094,14 @@ ordered-binary@^1.2.4:
   resolved "https://registry.npmjs.org/ordered-binary/-/ordered-binary-1.2.5.tgz"
   integrity sha512-djRmZoEpOGvIRW7ufsCDHtvcUa18UC9TxnPbHhSVFZHsoyg0dtut1bWtBZ/fmxdPN62oWXrV6adM7NoWU+CneA==
 
+out-of-character@^1.2.1:
+  version "1.2.1"
+  resolved "https://registry.yarnpkg.com/out-of-character/-/out-of-character-1.2.1.tgz#383bf683e58f654ee1f348029367edf5c79ba87d"
+  integrity sha512-clqCX4lNQa5Qr7urMNej2DbKVt+SO5CZ9Sq4XYEJ04qzvDHA4yFMhz0F+vLrfxO89640x8W56D7wtNoAgCCcAA==
+  dependencies:
+    colorette "1.2.2"
+    glob "7.1.7"
+
 p-each-series@^2.1.0:
   version "2.2.0"
   resolved "https://registry.npmjs.org/p-each-series/-/p-each-series-2.2.0.tgz"