diff --git a/apps/vectorcraft/src/main.rs b/apps/vectorcraft/src/main.rs
index e5a3736d..8d827d24 100644
--- a/apps/vectorcraft/src/main.rs
+++ b/apps/vectorcraft/src/main.rs
@@ -95,6 +95,11 @@ impl eframe::App for App {
             self.app.titlebar_inset = inset.unwrap_or(mac_window::DEFAULT_INSET);
         }
         file_access::unconfined(|| self.app.ui(ui));
+        // Preferences are written when confirmed, not only at exit: a session ended any other way
+        // (the system shutting down, the process ended or crashing) used to lose them (#1747).
+        if self.app.take_prefs_changed() {
+            file_access::unconfined(|| save_prefs(&self.app));
+        }
         // Not while a file dialog's sheet has the keyboard: its name field's composition would go.
         #[cfg(target_os = "macos")]
         if !self.app.file_dialog_open() && self.app.take_ime_discard() {
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index 6ed6b440..ebc4c123 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -425,6 +425,8 @@ pub struct VectorcraftApp {
     pub(crate) ime_marked: Option<String>,
     /// The IME must drop its marked text (see [`Self::take_ime_discard`]).
     pub(crate) ime_discard: bool,
+    /// Preferences were confirmed (see [`Self::take_prefs_changed`]).
+    pub(crate) prefs_changed: bool,
     /// A numeric field is being scrubbed: the document's edits meanwhile are one undo step
     /// ([`scrub::begin_frame`]).
     scrub_group: bool,
@@ -518,6 +520,7 @@ impl VectorcraftApp {
             synthetic_modifiers: false,
             ime_marked: None,
             ime_discard: false,
+            prefs_changed: false,
             scrub_group: false,
             automation_roots: None,
             synthetic_frame: false,
@@ -857,6 +860,12 @@ impl VectorcraftApp {
         std::mem::take(&mut self.ime_discard)
     }
 
+    /// Was Preferences confirmed since the last call? The host then writes the preferences file,
+    /// so what the user just set survives a session that doesn't end with a normal quit (#1747).
+    pub fn take_prefs_changed(&mut self) -> bool {
+        std::mem::take(&mut self.prefs_changed)
+    }
+
     /// Linked files another app changed while their document is open: every two seconds, and as
     /// soon as the window comes back to the front, stamp the active document's linked files on a
     /// worker thread and act on the changed ones as Preferences › File Handling › Update Links
diff --git a/crates/ui-egui/src/prefs_dialog.rs b/crates/ui-egui/src/prefs_dialog.rs
index 0e2bb93a..a4b049c9 100644
--- a/crates/ui-egui/src/prefs_dialog.rs
+++ b/crates/ui-egui/src/prefs_dialog.rs
@@ -45,6 +45,7 @@ pub fn confirm(app: &mut VectorcraftApp) -> Result<Value, String> {
     app.ui.task_bar = d.fields.get("__taskBar").and_then(Value::as_bool).unwrap_or(app.ui.task_bar);
     app.ui.dialog = None;
     app.ui.engine_prefs = app.session.prefs.to_json();
+    app.prefs_changed = true;
     Ok(Value::Null)
 }
 
@@ -557,7 +558,10 @@ mod tests {
         assert!(shown.iter().any(|t| t == "Automatic"), "{shown:?}");
         assert!(shown.iter().any(|t| t == "Applies the next time VectorCraft starts."), "{shown:?}");
         a.ui.dialog.as_mut().unwrap().fields.insert("gpuPreference".into(), json!("highPerformance"));
+        assert!(!a.take_prefs_changed(), "nothing to write before OK");
         confirm(&mut a).unwrap();
+        assert!(a.take_prefs_changed(), "OK asks the host to write the preferences file");
+        assert!(!a.take_prefs_changed());
         assert_eq!(a.session.prefs.gpu_preference, "highPerformance");
         let saved: Value = serde_json::from_slice(&serde_json::to_vec(&a.ui).unwrap()).unwrap();
         assert_eq!(saved["engine_prefs"]["gpuPreference"], json!("highPerformance"));