diff --git a/crates/doc/src/variables.rs b/crates/doc/src/variables.rs
index 96bccbd0a..09682a106 100644
--- a/crates/doc/src/variables.rs
+++ b/crates/doc/src/variables.rs
@@ -117,7 +117,8 @@ pub struct Variables {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub active_dataset: Option<String>,
     /// Lock Variables: while set, variables can't be defined, deleted or renamed. Objects can
-    /// still be bound to them and unbound, and datasets still change and apply.
+    /// still be bound to them and unbound, and datasets still change and apply, except that an
+    /// import whose header would define a variable is refused.
     #[serde(default, skip_serializing_if = "std::ops::Not::not")]
     pub locked: bool,
 }
diff --git a/crates/engine/src/cmd/variablecmds.rs b/crates/engine/src/cmd/variablecmds.rs
index da1eb33a7..377b30190 100644
--- a/crates/engine/src/cmd/variablecmds.rs
+++ b/crates/engine/src/cmd/variablecmds.rs
@@ -647,7 +647,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Lock Variables",
             ["Window", "Variables"],
             None,
-            "{locked?: bool} lock or unlock the variables (default: toggle); saved with the document; a change is one undo step. While locked, variable.define, variable.delete, variable.rename, variable.make…Dynamic and a variable.loadLibrary that would delete or define a variable are refused; binding, unbinding and the dataset commands still run → {locked}",
+            "{locked?: bool} lock or unlock the variables (default: toggle); saved with the document; a change is one undo step. While locked, variable.define, variable.delete, variable.rename, variable.make…Dynamic and a variable.loadLibrary that would delete or define a variable are refused; binding, unbinding and the dataset commands still run, except a dataset.import whose header would define a variable → {locked}",
             has_doc,
             lock
         ),
diff --git a/crates/engine/src/tests/variables.rs b/crates/engine/src/tests/variables.rs
index 33d3ac535..5e9fc7182 100644
--- a/crates/engine/src/tests/variables.rs
+++ b/crates/engine/src/tests/variables.rs
@@ -409,7 +409,8 @@ fn make_dynamic_errors_name_the_command() {
 }
 
 /// Lock Variables refuses defining, deleting and renaming variables, Make … Dynamic included,
-/// while binding, unbinding and the dataset commands still run.
+/// while binding, unbinding and the dataset commands still run (an import that would define a
+/// variable is refused; see `locked_variables_refuse_header_cells_that_define_variables`).
 #[test]
 fn locked_variables_refuse_new_deleted_and_renamed_variables() {
     let mut s = session();
@@ -453,6 +454,14 @@ fn locked_variables_refuse_new_deleted_and_renamed_variables() {
     s.execute("variable.define", &json!({"name": "Other", "kind": "text"})).unwrap();
 }
 
+/// `variable.lock`'s params text names the dataset command it refuses: an import whose header
+/// would define a variable.
+#[test]
+fn the_lock_params_text_names_the_refused_import() {
+    let params = cmd::find_command("variable.lock").unwrap().params;
+    assert!(params.contains("the dataset commands still run, except a dataset.import whose header would define a variable"), "{params}");
+}
+
 /// Locking is an undo step only when it changes the state, and the lock is saved with the
 /// document: a file saved locked opens locked, and a file without the key opens unlocked.
 #[test]