diff --git a/dexlib2/src/main/java/org/jf/dexlib2/base/reference/BaseTypeReference.java b/dexlib2/src/main/java/org/jf/dexlib2/base/reference/BaseTypeReference.java
index 1d5d6f56..22cb0e78 100644
--- a/dexlib2/src/main/java/org/jf/dexlib2/base/reference/BaseTypeReference.java
+++ b/dexlib2/src/main/java/org/jf/dexlib2/base/reference/BaseTypeReference.java
@@ -57,5 +57,5 @@ public abstract class BaseTypeReference implements TypeReference {
     @Override public int length() { return getType().length(); }
     @Override public char charAt(int index) { return getType().charAt(index); }
     @Override public CharSequence subSequence(int start, int end) { return getType().subSequence(start, end); }
-    @Override public String toString() { return getType(); }
+    @Override @Nonnull public String toString() { return getType(); }
 }