diff --git a/crates/script/src/runtime.rs b/crates/script/src/runtime.rs
index c7559856..5fad8a07 100644
--- a/crates/script/src/runtime.rs
+++ b/crates/script/src/runtime.rs
@@ -547,9 +547,9 @@ pub(crate) fn script_error(e: &boa_engine::JsError, ctx: &mut Context, file: &st
     ScriptError { message, line, column, file: file.to_string() }
 }
 
-/// Line and column of an error: `at line N, col M` (syntax errors), else the innermost backtrace
-/// frame in the user's script (`file:line:col`), else (names boa can't place) the first use of
-/// the undefined name in `code`.
+/// Line and column of an error: `at line N, col M` (syntax errors), else the first use of an
+/// undefined name in `code` (boa places those at a function's start), else the innermost backtrace
+/// frame in the user's script (`file:line:col`).
 fn position(msg: &str, file: &str, code: &str) -> (Option<u32>, Option<u32>) {
     if let Some(i) = msg.find("at line ") {
         let rest = &msg[i + 8..];
@@ -563,28 +563,39 @@ fn position(msg: &str, file: &str, code: &str) -> (Option<u32>, Option<u32>) {
         let mut it = l[i..].split([':', ')']);
         Some((it.next()?.parse().ok()?, it.next()?.parse().ok()?))
     };
+    // `ReferenceError: name is not defined`: boa places it at the start of the function that reads
+    // the name, so the first use of the name in the code is the better position (#1063).
+    let first = msg.lines().next().unwrap_or("");
+    let undefined = first.split("ReferenceError: ").nth(1).and_then(|r| r.split(" is not defined").next());
+    if let Some(at) = undefined.and_then(|name| first_use(name, code)) {
+        return (Some(at.0), Some(at.1));
+    }
     let frames: Vec<&str> = msg.lines().skip(1).collect();
     if let Some((a, b)) = frames.iter().find_map(|l| pick(l)).or_else(|| msg.lines().next().and_then(pick)) {
         return (Some(a), Some(b));
     }
-    // `ReferenceError: name is not defined` without a position.
-    let first = msg.lines().next().unwrap_or("");
-    if let Some(name) = first.split("ReferenceError: ").nth(1).and_then(|r| r.split(" is not defined").next()) {
-        for (n, line) in code.lines().enumerate() {
-            let b = line.as_bytes();
-            let mut from = 0;
-            while let Some(i) = line[from..].find(name).map(|i| i + from) {
-                let before = i.checked_sub(1).map(|j| b[j]);
-                let after = b.get(i + name.len()).copied();
-                let ident = |c: u8| c.is_ascii_alphanumeric() || c == b'_' || c == b'$';
-                if !before.is_some_and(|c| ident(c) || c == b'.') && !after.is_some_and(ident) {
-                    return (Some(n as u32 + 1), Some(i as u32 + 1));
-                }
-                from = i + name.len();
+    (None, None)
+}
+
+/// The first use of `name` as a whole identifier in `code`, as a 1-based line and column.
+fn first_use(name: &str, code: &str) -> Option<(u32, u32)> {
+    if name.is_empty() {
+        return None;
+    }
+    let ident = |c: u8| c.is_ascii_alphanumeric() || c == b'_' || c == b'$';
+    for (n, line) in code.lines().enumerate() {
+        let b = line.as_bytes();
+        let mut from = 0;
+        while let Some(i) = line.get(from..).and_then(|rest| rest.find(name)).map(|i| i + from) {
+            let before = i.checked_sub(1).and_then(|j| b.get(j).copied());
+            let after = b.get(i + name.len()).copied();
+            if !before.is_some_and(|c| ident(c) || c == b'.') && !after.is_some_and(ident) {
+                return Some((n as u32 + 1, i as u32 + 1));
             }
+            from = i + name.len();
         }
     }
-    (None, None)
+    None
 }
 
 /// Evaluate `code` in `ctx` and convert the result.
diff --git a/crates/script/src/tests.rs b/crates/script/src/tests.rs
index 303bd820..a54e5742 100644
--- a/crates/script/src/tests.rs
+++ b/crates/script/src/tests.rs
@@ -142,6 +142,24 @@ fn errors_report_line_and_column() {
     assert_eq!(e.line, Some(3), "{e:?}");
 }
 
+/// A script wrapped in a function (the usual `(function () { ... })();` shape) reports the line
+/// that failed, not the wrapper's line (#1063).
+#[test]
+fn errors_inside_a_function_wrapper_report_the_failing_line() {
+    let mut s = session();
+    let o = run_code(&mut s, "(function () {\n  var a = 1;\n  throw new Error('inside');\n})();\n", "thrown.jsx");
+    let e = o.error.expect("thrown");
+    assert_eq!(e.message, "inside");
+    assert_eq!(e.line, Some(3), "{e:?}");
+    let o = run_code(&mut s, "(function () {\n  var a = 1;\n  nope.call();\n})();\n", "reference.jsx");
+    let e = o.error.expect("reference error");
+    assert_eq!(e.line, Some(3), "{e:?}");
+    let o = run_code(&mut s, "(function () {\n  var c = app.project.items.addComp('C', 10, 10, 1, 1, 24);\n  c.layer(5);\n})();\n", "range.jsx");
+    let e = o.error.expect("range error");
+    assert!(e.message.contains("out of range"), "{e:?}");
+    assert_eq!(e.line, Some(3), "{e:?}");
+}
+
 #[test]
 fn match_names_and_lookups() {
     let mut s = session();