diff --git a/.gitignore b/.gitignore
index 2e3d0f9..756c54b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,6 @@ result
 tmp/
 tests/.DS_Store
 .DS_Store
+
+# skills
+.github/skills/*
diff --git a/src/formatting.rs b/src/formatting.rs
index e75fcae..7fff267 100644
--- a/src/formatting.rs
+++ b/src/formatting.rs
@@ -133,6 +133,20 @@ impl<'a> Formatter<'a> {
         self.write_span(expr.span);
     }
 
+    /// Write an attribute expression while preserving a leading '@' sigil.
+    fn write_attribute_span(&mut self, expr: &Expression) {
+        let mut start = expr.span.start;
+
+        if start > 0 && self.source[start - 1] == b'@' {
+            start -= 1;
+        }
+
+        self.write_span(Span {
+            start,
+            end: expr.span.end,
+        });
+    }
+
     // ─────────────────────────────────────────────────────────────────────────────
     // Comment handling
     // ─────────────────────────────────────────────────────────────────────────────
@@ -383,7 +397,7 @@ impl<'a> Formatter<'a> {
 
             Expr::AttributeBlock(attr_block) => {
                 for attr in &attr_block.attributes {
-                    self.write_span(attr.expr.span);
+                    self.write_attribute_span(&attr.expr);
                     self.newline();
                 }
                 self.format_expression(&attr_block.item);
diff --git a/tests/fixtures/expected/issue100.nu b/tests/fixtures/expected/issue100.nu
new file mode 100644
index 0000000..cce970d
--- /dev/null
+++ b/tests/fixtures/expected/issue100.nu
@@ -0,0 +1,2 @@
+@category a
+def a [] { }
diff --git a/tests/fixtures/input/issue100.nu b/tests/fixtures/input/issue100.nu
new file mode 100644
index 0000000..cce970d
--- /dev/null
+++ b/tests/fixtures/input/issue100.nu
@@ -0,0 +1,2 @@
+@category a
+def a [] { }
diff --git a/tests/ground_truth.rs b/tests/ground_truth.rs
index 300ed0b..360be8b 100644
--- a/tests/ground_truth.rs
+++ b/tests/ground_truth.rs
@@ -806,4 +806,5 @@ issue_fixture_tests!(
     ("issue94", issue94_test, idempotency_issue94_test),
     ("issue95", issue95_test, idempotency_issue95_test),
     ("issue97", issue97_test, idempotency_issue97_test),
+    ("issue100", issue100_test, idempotency_issue100_test),
 );