diff --git a/crates/engine/src/cmd/effect.rs b/crates/engine/src/cmd/effect.rs
index f41ba3f9c..2d73a2801 100644
--- a/crates/engine/src/cmd/effect.rs
+++ b/crates/engine/src/cmd/effect.rs
@@ -35,6 +35,14 @@ fn plugins_list(s: &mut Session, _: &Value) -> Result<Value> {
 /// folder) through the host's loader ([`Session::plugin_loader`]).
 fn plugins_load(s: &mut Session, p: &Value) -> Result<Value> {
     let c = "effect.plugins.load";
+    // A plug-in is code, and a file that fails to load comes back in the error: a script may
+    // load one only with the access it would need to read and write files anywhere.
+    if s.running_for_script() && !s.prefs.scripting.allow_scripts_write_files {
+        return Err(bad(
+            c,
+            "scripts can't load effect plug-ins unless Settings ▸ Scripting & Expressions ▸ Allow Scripts to Write Files and Access Network is on",
+        ));
+    }
     let loader = s.plugin_loader.ok_or_else(|| EngineError::Other("WebAssembly effect plug-ins are not available in this build".into()))?;
     let files: Vec<String> = match (str_p(p, "path"), str_p(p, "folder")) {
         (Some(path), _) => vec![path.to_string()],
diff --git a/crates/engine/src/tests/settings.rs b/crates/engine/src/tests/settings.rs
index 5e38c90a3..0dac9e6ed 100644
--- a/crates/engine/src/tests/settings.rs
+++ b/crates/engine/src/tests/settings.rs
@@ -651,6 +651,18 @@ fn context_shortcuts_on_the_same_keys_conflict() {
     assert!(t.conflicts(b, "F9").iter().any(|c| c.key == "test.paint" && !c.overrides));
 }
 
+/// A script loads effect plug-ins only with Allow Scripts to Write Files on.
+#[test]
+fn scripts_load_effect_plugins_only_with_file_access() {
+    let mut s = Session::default();
+    let p = json!({"path": "/etc/hostname"});
+    let e = s.execute_for_script("effect.plugins.load", p.clone()).unwrap_err().to_string();
+    assert!(e.contains("Allow Scripts to Write Files"), "{e}");
+    s.prefs.scripting.allow_scripts_write_files = true;
+    let e = s.execute_for_script("effect.plugins.load", p).unwrap_err().to_string();
+    assert!(!e.contains("Allow Scripts to Write Files"), "{e}");
+}
+
 // ---------------------------------------------------------------- auto-save / recovery
 
 /// The names in `d`, sorted.