diff --git a/mlir/test/IR/traits.mlir b/mlir/test/IR/traits.mlir
--- a/mlir/test/IR/traits.mlir
+++ b/mlir/test/IR/traits.mlir
@@ -448,7 +448,7 @@
 // -----
 
 func @failedResultSizeAttrWrongCount() {
-  // expected-error @+1 {{'result_segment_sizes' attribute for specifying result segments must have 4 elements}}
+  // expected-error @+1 {{'result_segment_sizes' attribute for specifying result segments must have 4 elements, but got 3}}
   %0:4 = "test.attr_sized_results"() {result_segment_sizes = dense<[2, 1, 1]>: vector<3xi32>} : () -> (i32, i32, i32, i32)
 }
 
diff --git a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
--- a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
@@ -2211,7 +2211,7 @@
     auto numElements = sizeAttr.getType().cast<::mlir::ShapedType>().getNumElements();
     if (numElements != {1})
       return emitError(loc, "'{0}' attribute for specifying {2} segments "
-                       "must have {1} elements");
+                       "must have {1} elements, but got ") << numElements;
   }
   )";