diff --git a/src/lib.rs b/src/lib.rs
index bf70fe5..e60f051 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -600,9 +600,8 @@ pub(crate) fn eat_expr<I: Iterator<Item = Token>>(
             }
             '#' => {
                 values.push(toks.next().unwrap());
-                let next = toks.next().unwrap();
-                values.push(next);
-                if next.kind == '{' {
+                if toks.peek().unwrap().kind == '{' {
+                    values.push(toks.next().unwrap());
                     values.extend(eat_interpolation(toks));
                 }
             }
diff --git a/src/selector.rs b/src/selector.rs
index 280dd3f..836915c 100644
--- a/src/selector.rs
+++ b/src/selector.rs
@@ -269,7 +269,7 @@ impl<'a> SelectorParser<'a> {
                 }
                 '#' => {
                     tokens.next();
-                    if tokens.peek().unwrap().kind == '{' {
+                    if tokens.peek().is_some() && tokens.peek().unwrap().kind == '{' {
                         tokens.next();
                         self.is_interpolated = true;
                         self.tokens_to_selectors(
diff --git a/tests/selectors.rs b/tests/selectors.rs
index 840dcfd..a910d7d 100644
--- a/tests/selectors.rs
+++ b/tests/selectors.rs
@@ -305,3 +305,8 @@ test!(
 // );
 test!(allows_id_start_with_number, "#2foo {\n  color: red;\n}\n");
 test!(allows_id_only_number, "#2 {\n  color: red;\n}\n");
+test!(
+    id_interpolation,
+    "$zzz: zzz;\n##{$zzz} {\n  a: b;\n}\n",
+    "#zzz {\n  a: b;\n}\n"
+);