diff --git a/mlir/include/mlir/IR/OperationSupport.h b/mlir/include/mlir/IR/OperationSupport.h
--- a/mlir/include/mlir/IR/OperationSupport.h
+++ b/mlir/include/mlir/IR/OperationSupport.h
@@ -483,6 +483,7 @@
 
   /// Add an attribute with the specified name.
   void addAttribute(Identifier name, Attribute attr) {
+    assert(attr && "unexpected null attribute");
     attributes.append(name, attr);
   }
 
diff --git a/mlir/lib/IR/Operation.cpp b/mlir/lib/IR/Operation.cpp
--- a/mlir/lib/IR/Operation.cpp
+++ b/mlir/lib/IR/Operation.cpp
@@ -176,6 +176,10 @@
       attrs(attributes) {
   assert(attributes && "unexpected null attribute dictionary");
 #ifndef NDEBUG
+  llvm::for_each(attributes.getValue(), [](NamedAttribute idAndAttr) {
+    assert(idAndAttr.second &&
+           "unexpected null attribute in attribute dictionary");
+  });
   if (!getDialect() && !getContext()->allowsUnregisteredDialects())
     llvm::report_fatal_error(
         name.getStringRef() +