diff --git a/isthmus/src/main/java/io/substrait/isthmus/OuterReferenceResolver.java b/isthmus/src/main/java/io/substrait/isthmus/OuterReferenceResolver.java
index eeb645175..79410ea47 100644
--- a/isthmus/src/main/java/io/substrait/isthmus/OuterReferenceResolver.java
+++ b/isthmus/src/main/java/io/substrait/isthmus/OuterReferenceResolver.java
@@ -29,15 +29,8 @@ public OuterReferenceResolver() {
     fieldAccessDepthMap = new IdentityHashMap<>();
   }
 
-  public int getStepsOut(RexFieldAccess fieldAccess) {
-    return fieldAccessDepthMap.get(fieldAccess);
-  }
-
-  public RelNode apply(RelNode r) {
-    return reverseAccept(r);
-  }
-
-  public Map<RexFieldAccess, Integer> getFieldAccessDepthMap() {
+  public Map<RexFieldAccess, Integer> apply(RelNode r) {
+    reverseAccept(r);
     return fieldAccessDepthMap;
   }
 
diff --git a/isthmus/src/main/java/io/substrait/isthmus/SubstraitRelVisitor.java b/isthmus/src/main/java/io/substrait/isthmus/SubstraitRelVisitor.java
index 835d8493d..87dde05c4 100644
--- a/isthmus/src/main/java/io/substrait/isthmus/SubstraitRelVisitor.java
+++ b/isthmus/src/main/java/io/substrait/isthmus/SubstraitRelVisitor.java
@@ -609,8 +609,7 @@ public Rel visitOther(RelNode other) {
 
   protected void popFieldAccessDepthMap(RelNode root) {
     final OuterReferenceResolver resolver = new OuterReferenceResolver();
-    resolver.apply(root);
-    fieldAccessDepthMap = resolver.getFieldAccessDepthMap();
+    fieldAccessDepthMap = resolver.apply(root);
   }
 
   public Integer getFieldAccessDepth(RexFieldAccess fieldAccess) {
diff --git a/isthmus/src/test/java/io/substrait/isthmus/OuterReferenceResolverTest.java b/isthmus/src/test/java/io/substrait/isthmus/OuterReferenceResolverTest.java
index b24401a9e..a804aafb1 100644
--- a/isthmus/src/test/java/io/substrait/isthmus/OuterReferenceResolverTest.java
+++ b/isthmus/src/test/java/io/substrait/isthmus/OuterReferenceResolverTest.java
@@ -32,10 +32,7 @@ private static void validateOuterRef(
 
   private static Map<RexFieldAccess, Integer> buildOuterFieldRefMap(final RelNode root) {
     final OuterReferenceResolver resolver = new OuterReferenceResolver();
-    final Map<RexFieldAccess, Integer> fieldAccessDepthMap = resolver.getFieldAccessDepthMap();
-    Assertions.assertEquals(0, fieldAccessDepthMap.size());
-    resolver.apply(root);
-    return fieldAccessDepthMap;
+    return resolver.apply(root);
   }
 
   @Test