diff --git a/mlir/lib/IR/OperationSupport.cpp b/mlir/lib/IR/OperationSupport.cpp
--- a/mlir/lib/IR/OperationSupport.cpp
+++ b/mlir/lib/IR/OperationSupport.cpp
@@ -873,6 +873,9 @@
     //   - Successors
     for (unsigned i = 0, e = op->getNumSuccessors(); i != e; ++i)
       addDataToHash(hasher, op->getSuccessor(i));
+    //   - Result types
+    for (Type t : op->getResultTypes())
+      addDataToHash(hasher, t);
   });
   hash = hasher.result();
 }