diff --git a/Makefile b/Makefile
index 55f8023..00dd308 100644
--- a/Makefile
+++ b/Makefile
@@ -896,8 +896,8 @@ check-symbols: $(STARTUP_FILES) libc
 	@# clang 16 for -mcpu=generic.
 	@# TODO: Undefine __wasm_multivalue__ and __wasm_reference_types__, that are new to
 	@# clang 19 for -mcpu=generic.
-	@# TODO: Undefine __wasm_nontrapping_fptoint__ and __wasm_bulk_memory__, that are
-	@# new to clang 20.
+	@# TODO: Undefine __wasm_nontrapping_fptoint__, __wasm_bulk_memory__ and
+	@# __wasm_bulk_memory_opt__, that are new to clang 20.
 	@# TODO: As of clang 16, __GNUC_VA_LIST is #defined without a value.
 	$(CC) $(CFLAGS) "$(SYSROOT_SHARE)/include-all.c" \
 	    -isystem $(SYSROOT_INC) \
@@ -918,6 +918,7 @@ check-symbols: $(STARTUP_FILES) libc
 	    -U__wasm_reference_types__ \
 	    -U__wasm_nontrapping_fptoint__ \
 	    $(if $(filter-out expected/wasm32-wasip1-threads,$(EXPECTED_TARGET_DIR)),-U__wasm_bulk_memory__) \
+	    -U__wasm_bulk_memory_opt__ \
 	    -U__GNUC__ \
 	    -U__GNUC_MINOR__ \
 	    -U__GNUC_PATCHLEVEL__ \