diff --git a/carcara/src/ast/polyeq.rs b/carcara/src/ast/polyeq.rs
index 4c2df07d..fe0be2ce 100644
--- a/carcara/src/ast/polyeq.rs
+++ b/carcara/src/ast/polyeq.rs
@@ -482,7 +482,7 @@ impl DeBruijnMap {
     }
 
     fn is_empty(&self) -> bool {
-        self.indices.0.is_empty() && self.indices.1.is_empty() && self.counter.is_empty()
+        self.indices.0.is_empty() && self.indices.1.is_empty()
     }
 
     fn push(&mut self) {
diff --git a/carcara/src/utils.rs b/carcara/src/utils.rs
index 98d52e6b..ac601b93 100644
--- a/carcara/src/utils.rs
+++ b/carcara/src/utils.rs
@@ -111,12 +111,8 @@ impl<K, V> HashMapStack<K, V> {
         Self { scopes: vec![IndexMap::new()] }
     }
 
-    pub fn height(&self) -> usize {
-        self.scopes.len()
-    }
-
     pub fn is_empty(&self) -> bool {
-        self.height() == 0
+        self.scopes.iter().all(IndexMap::is_empty)
     }
 
     pub fn push_scope(&mut self) {