diff --git a/src/main/java/com/android/tools/r8/graph/DexDefinition.java b/src/main/java/com/android/tools/r8/graph/DexDefinition.java
index 9127b94..82dfc12 100644
--- a/src/main/java/com/android/tools/r8/graph/DexDefinition.java
+++ b/src/main/java/com/android/tools/r8/graph/DexDefinition.java
@@ -12,16 +12,6 @@
  */
 public abstract class DexDefinition extends DexItem {
 
-  @Override
-  public boolean isDexDefinition() {
-    return true;
-  }
-
-  @Override
-  public DexDefinition asDexDefinition() {
-    return this;
-  }
-
   public boolean isDexClass() {
     return false;
   }
diff --git a/src/main/java/com/android/tools/r8/graph/DexItem.java b/src/main/java/com/android/tools/r8/graph/DexItem.java
index 8aa09b6..eb8e150 100644
--- a/src/main/java/com/android/tools/r8/graph/DexItem.java
+++ b/src/main/java/com/android/tools/r8/graph/DexItem.java
@@ -64,22 +64,6 @@
     return toString();
   }
 
-  public boolean isDexReference() {
-    return false;
-  }
-
-  public DexReference asDexReference() {
-    return null;
-  }
-
-  public boolean isDexDefinition() {
-    return false;
-  }
-
-  public DexDefinition asDexDefinition() {
-    return null;
-  }
-
   static <T extends DexItem> Stream<T> filter(Stream<DexItem> stream, Class<T> clazz) {
     return stream.filter(clazz::isInstance).map(clazz::cast);
   }
diff --git a/src/main/java/com/android/tools/r8/graph/DexReference.java b/src/main/java/com/android/tools/r8/graph/DexReference.java
index af7dc20..d51810e 100644
--- a/src/main/java/com/android/tools/r8/graph/DexReference.java
+++ b/src/main/java/com/android/tools/r8/graph/DexReference.java
@@ -13,16 +13,6 @@
  */
 public abstract class DexReference extends IndexedDexItem {
 
-  @Override
-  public boolean isDexReference() {
-    return true;
-  }
-
-  @Override
-  public DexReference asDexReference() {
-    return this;
-  }
-
   public boolean isDexType() {
     return false;
   }
diff --git a/src/main/java/com/android/tools/r8/ir/code/InvokeStatic.java b/src/main/java/com/android/tools/r8/ir/code/InvokeStatic.java
index c8f8b49..5d782c3 100644
--- a/src/main/java/com/android/tools/r8/ir/code/InvokeStatic.java
+++ b/src/main/java/com/android/tools/r8/ir/code/InvokeStatic.java
@@ -32,7 +32,7 @@
 
   public InvokeStatic(DexMethod target, Value result, List<Value> arguments) {
     this(target, result, arguments, false);
-    assert target.asDexReference().asDexMethod().proto.parameters.size() == arguments.size();
+    assert target.proto.parameters.size() == arguments.size();
   }
 
   public InvokeStatic(DexMethod target, Value result, List<Value> arguments, boolean itf) {