diff --git a/.changes/css-inliner-octal.md b/.changes/css-inliner-octal.md
new file mode 100644
index 000000000..69971bcea
--- /dev/null
+++ b/.changes/css-inliner-octal.md
@@ -0,0 +1,5 @@
+---
+"tauri": patch
+---
+
+Replace `\` with `\\` in css assets that are lazy loaded. Since these are injected in a template literal, backslashes must be escaped. Backslashes are sometimes used for octal sequences in CSS.
diff --git a/tauri/src/endpoints/asset.rs b/tauri/src/endpoints/asset.rs
index 8c8e4940d..b1d54f32f 100644
--- a/tauri/src/endpoints/asset.rs
+++ b/tauri/src/endpoints/asset.rs
@@ -76,7 +76,8 @@ pub fn load(
                   document.getElementsByTagName("head")[0].appendChild(css);
                 }})(`{css}`)
               "#,
-              css = asset_str
+              // Escape octal sequences, which aren't allowed in template literals
+              css = asset_str.replace("\\", "\\\\").as_str()
             ));
           } else {
             webview_ref.eval(asset_str);