diff --git a/mlir/tools/mlir-opt/mlir-opt.cpp b/mlir/tools/mlir-opt/mlir-opt.cpp
--- a/mlir/tools/mlir-opt/mlir-opt.cpp
+++ b/mlir/tools/mlir-opt/mlir-opt.cpp
@@ -133,7 +133,9 @@
 #endif
   DialectRegistry registry;
   registerAllDialects(registry);
+#ifdef MLIR_INCLUDE_TESTS
   registerTestDialect(registry);
+#endif
   return failed(MlirOptMain(argc, argv, "MLIR modular optimizer driver\n",
                             registry,
                             /*preloadDialectsInContext=*/false));