diff --git a/mlir/CMakeLists.txt b/mlir/CMakeLists.txt
index 6be0b35338c05..28018350cb43d 100644
--- a/mlir/CMakeLists.txt
+++ b/mlir/CMakeLists.txt
@@ -48,6 +48,13 @@ endif()
 check_c_compiler_flag("-Werror=implicit-function-declaration" C_SUPPORTS_WERROR_IMPLICIT_FUNCTION_DECLARATION)
 append_if(C_SUPPORTS_WERROR_IMPLICIT_FUNCTION_DECLARATION "-Werror=implicit-function-declaration" CMAKE_C_FLAGS)
 
+# Forbid mismatch between declaration and definition for class vs struct. This is
+# harmless on Unix systems, but it'll be a ticking bomb for MSVC/Windows systems
+# where it creeps into the ABI.
+check_c_compiler_flag("-Werror=mismatched-tags" C_SUPPORTS_WERROR_MISMATCHED_TAGS)
+append_if(C_SUPPORTS_WERROR_MISMATCHED_TAGS "-Werror=mismatched-tags" CMAKE_C_FLAGS)
+append_if(C_SUPPORTS_WERROR_MISMATCHED_TAGS "-Werror=mismatched-tags" CMAKE_CXX_FLAGS)
+
 # Installing the headers and docs needs to depend on generating any public
 # tablegen'd targets.
 # mlir-generic-headers are dialect-independent.