diff --git a/tools/llvm-diff/DifferenceEngine.h b/tools/llvm-diff/DifferenceEngine.h
index 1609bd5..6eefb06 100644
--- a/tools/llvm-diff/DifferenceEngine.h
+++ b/tools/llvm-diff/DifferenceEngine.h
@@ -118,7 +118,7 @@
       virtual void logd(const DiffLogBuilder &Log) = 0;
 
     protected:
-      ~Consumer() {}
+      virtual ~Consumer() {}
     };
 
     /// A RAII object for recording the current context.
@@ -141,7 +141,7 @@
       virtual bool operator()(Value *L, Value *R) = 0;
 
     protected:
-      ~Oracle() {}
+      virtual ~Oracle() {}
     };
 
     DifferenceEngine(LLVMContext &context, Consumer &consumer)